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Planning for DrivePool


zeroibis

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I have been looking at DrivePool for sometime and as I get closer to a new build I had some things I wanted to verify:

1) Drive pool will work with backblaze and I can backup my pool just as if it was a normal HDD.

2) It is not possible to have real time duplication enabled and only use a single physical SSD for caching. (I wish you could just use a single drive as a literal write cache where it taking the data off the cache as fast as it can and placing it on a pool with real time duplication, in this way your SSD functions the same as the DDR cache on a raid controller where there is no duplication in the DDR.)

3) Close to real time duplication is possible when using a single physical SSD for caching. Can I still have real time on the drives it is writing to? How close to real time can we get?

4) Can not preform a single move operation that is larger than the SSD cache to any pool using said SSD cache. Now I use terracopy so I can override this and preform the move operation anyways but what will occur in this case? What if I am moving a single file that is larger than the SSD cache?

5) Read operations take advantage of multiple drives and can do so at the block level. If I have a large file that is on a pool containing 2 drives with duplication it will read the file from both drives. If I had a file on a pool with duplication and 4 drives (assuming there is only 1 duplicate) it would read at the same speed because the file is only stored on 2 of the 4 drives and thus read speeds are limited by the number of duplicates and not the number of drives in the pool (as compared to raid 10).

6) In a raid 10 like pool where you have at least 4 drives and file duplication on if you were to lose two drives at the same time and those drives were duplicates of each other there is no function of the program that can tell you what files you have now lost. (This seems like something that would make a great feature)

7) Possible solution to ensure you have backups for the scenario in #6 would be to have backblaze backup each duplication pool individually so that if you lost all the drives in that pool the restore is very simple. A problem with this is that windows can only have 26 drive letters. Thus you could have a maximum of 24 duplication pools 1 pool of the duplication pools and your C: drive. Perhaps it is possible to get around this if you link a duplication pool to be a folder on your C drive, I am not sure if Backblaze would follow it. Basically at minimum for example I could do the following:

  • Create duplication pool named "D Pool 1" of >=2 drives and assign it to drive Z
  • Create duplication pool named "D Pool 2" of >=2 drives and assign it to drive Y
  • Create pool containing D Pool 1 and D Pool 2 and assign it to drive D
  • Set backblaze to backup drive Z and Y (can it do this or will it fail to see the files?)
  • Now if you lose a duplication pool that was part of a larger pool it is easy to pull a backup of just that D Pool # from backblaze. In this way you do not need to worry about what files from the larger pool are missing because those files are in their own backup. If you have the freespace you can simply restore the files from your D Pool # backup to your larger pool and bam all your files are there now.

 

Sorry for so many questions, I just want to ensure that my understanding of how DrivePool operates is correct so that I am able to plan accordingly.

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I can't speak to BackBlaze, but I'll try with the others:

2)  Yes you can use a single SSD as a pool cache, and use real-time duplication on the other pool drives.  However, to get the nearly-real-time functionality you want, you would want to use a L2 SSD cache with a product like Primocache.  It does real block-level caching in either RAM (L1 cache), or against a SSD (L2 cache) at whatever intervals you setup.  It can cache the write commands made to the Pool and immediately transfer the data across as fast as the drives will take it.  I use the software on virtually all my machines, and have been since before it was even Beta.  Great stuff, worth the price.

3)  See #2.  I am fairly sure that with real-time duplication set on the main pool drives, any writes directly to them are literally synchronous.

4)  You're right in assuming that if you have a file to be written to the pool that is larger than the space on the SSD, you'll run into issues.  The reason is that the DP SSD cache is treated as another pool drive, just a front-load one so that all files land there first, THEN get migrated to the main pool drives after.  From this perspective, using Primocache and telling it to cache writes for only a few seconds before writing them (and then freeing the cache space) would be ideal.

5)  The read speed boost from duplication across pool drives is limited to the number of drives the file resides on.  2 drives might get you a small boost, whereas 6 drives might get you a substantial boost.  It also depends on the size of the file and how long you can sustain multiple reads from all drives it sits on.

6)  Correct - RAID functionality (beyond RAID 1 style duplication on either the entire pool or folders/files on it) isn't part of DrivePool.  For that I'd recommend software like SnapRAID, which computes parity across all drives and stores it on separate parity drives.  You can have anywhere from 1 parity drive (RAID 5) up to 6 parity drives (well beyond RAID 6 capabilities).  It is on-demand parity calculation software, so you run it on a schedule to update (I do mine nightly).  Works rather well, and is free.  Native duplication on the DP pool works well however, if you're willing to sacrifice the extra space to do it.

7)  You can mount as many drives as you want for Drivepool (and in fact SnapRAID) to use, simply use folder mount points.  You don't need to limit yourself to drive letters where the software is concerned.  They are assigned in the same place where you assign letters - you just create a folder for each on the drive you want them to appear before in Explorer, then assign it there.

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Ah very good to hear about the folder mount points, I suspect I will need to use a demo and verify that backblaze is able to to backup files discovered in such a folder. If that is the case it should be very easy to use backblaze as a backup solution for protecting individual mirrored pools. My focus here was to ensure that there was a simple to implant disaster recovery for when local file loss actually occurs. It seams the issue here is you need to make sure that you create all your duplication pools individually and then pool your pools so you can have 1 big drive. The con with this approach is that if and when 1 drive does fail the reaming drive that has the files will not automatically duplicate the files to other drives because those drives are outside the duplication pool. In this way it is not any better or worse than raid 10 from a reliability perspective except that unlike true raid 10 your not going to lose everything if two drives with the same content fail at the same time.

Now as far as extreme performance goes I suppose one could make a software raid 0 of X drives and a second raid 0 of X drives in windows disk management and then add the two resultant raid 0 drives to a duplication pool to create an effective raid 10 which would have the performance of X write speed and ~2X read. Logically in this case if you lost a drive from both raid 0 sets at the same time you would lose everything.

Nice to hear about Primocache that sounds like a great option!

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No need to create hierarchical pools when you use full Pool duplication.  Just one pool with X number of copies set.  If you set that number to the number of drives you use, you have a redundancy factor equal to your drive count, though that's a bit overkill in most situations.  No disaster recovery needed in this case - the pool just keeps on running and tries to evacuate the damaged disk if necessary.  You -could- make multiple child pools and mirror them inside the master pool, but I don't see any advantages vs Pool duplication for you, unless parts of your data have different needs (placement, duplication factor, etc).

That's why I use SnapRAID - conventional RAID solutions just can't protect like they used to, with the size of data we deal with today.  Two interesting and informative articles that show why this is true:

Consider for a moment if you have two pools setup - one a main pool with active data, and one a "mirror pool" for redundancy.  If you have a drive fail on the main, AND a drive fail on the mirror at the same time, you risk losing file(s).  That could happen with any number of child pools.  With software RAID (parity calculations), you can lose up to 6 drives at once and still be protected in SnapRAID if you set it up with that many parity drives.  One user of SnapRAID successfully recovered after a simultaneous loss of 4 drives.

Pool duplication is definitely viable, but you'd have to have a duplication factor of 5 or more on the entire pool to avoid that kind of disaster.  It's doable however, if you want to use Drivepool's duplication and the extra drives instead of a solution like SnapRAID.  With SnapRAID you can have a pool consisting of up to 42 data disks with just 6 parity disks, and STILL be protected.  That's an efficient use of resources.  A solution like SnapRAID however does require some downtime during disaster recovery, for it to rebuild replaced drives.  The flipside is that you have better overall utilization of storage space, and not so many duplicates hanging around.

On the side - I wouldn't recommend software RAID in Windows for this kind of data protection/use.  Between file duplication on the pool for increased read speeds, and a SSD handling L2 write caching with Primocache, you'd be set for instant offload of writes and faster reads.  Most networks in business use today are still 1Gbit, so can easily be saturated by 1-2 drives' activity with larger files.

Your solution will of course depend on how easy you want your disaster recovery to be - easier requires much more investment in resources.  :) 

And yeah, Primocache is a great piece of software for all kinds of drive caching.  It has a rather long free trial so you can test different setups.

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Yea I know that hierarchical pools are not required it is that they are ideal from a backup perspective. Take the following scenarios:

A) You have 8x 2tb drives in one big pool with file duplication. You have it set so there is 2 of every file. Now two drives in this pool fail. Only the data that was contained on both of these drives was lost. You however have no idea what this data was and so to recover you will need to pull an 8tb recovery and then tell it to skip any files it finds so that your restore will give you the files you are missing. Problem is that you need to have an 8tb recovery image sent to your house or download it.

B) You have 8x 2tb drives separated into 4 pools of 2 drives each where each pool has duplication. You configure backups to run on each of these individual pools. You then join these 4 pools into 1 large storage pool. You know that the data on each of the 4 smaller pools are exact copies of each other so now when 2 drives fail in a scenario that created data loss you can simply download the 2tb recovery of that individual pool.

Also if you really want to increase performance you could do:

C) You have 8x 2tb drives and separate them into 4x raid 0 arrays in disk manager. You then take the 4x 4tb arrays and create 2x duplication pools of 4tb each. You then configure backups to run on the duplication pools. You create a final pool of the 2x duplication pools. If two drives fail which are in the same duplication pool and on different raid 0 arrays you will need to restore 4tb of data but because you know what data was stored on that array you can easily obtain a 4tb recovery of just what you need. In addition you get a ~2x performance advantage.

D) You have 8x 2tb drives and separate them into 2x raid 0 arrays in disk manager. You then take the 2x 8tb arrays and create a duplication pool of 8tb total. If two drives fail and each is on a different raid 0 array you lose 8TB of data. You need to restore from your 8TB size backup.

 

Risk Analysis:

A) Lowest risk with up to 2tb lost but with a chance in single drive failures to evade file loss altogether if backup to other drives can be completed and same performance as B except that file restores will take longer and are more expensive if you need to have a restore drive shipped to you.

 Slightly more or less risky then A although in worst case for both you lose 2tb of data each and for the same performance you could actually under the right conditions lose 4 drives at the same time without data loss as long as none of them share a duplication pool. Benefit is that restores are significantly faster than A

C) Riskier than B in that you could lose twice as much data in the event of worst case two drive failure but it is still more reliable on average then A in that you could sustain up to 4 drive failures at the same time without any data loss if your lucky. You also get twice the performance. Your restore will be twice as slow as B but still twice as fast as option A.

D) The most risky option you can lose everything if one drive in each raid 0 fails. Restoring is the same process as with A but your actually restoring everything instead of just what is missing.

 

For my needs C may be the best option because I am transferring unedited RAW files and master video files from the server to client systems fir editing. The client systems are loading them on to 960/970 EVOs over 10GE network. So both read and write speeds are important to me. Trying to do an emergency recovery from parity data is too slow, it is faster to just have a backup HDD overnighted. Key here is what you find to be acceptable redundancy weather it be 2 drives or 6 drives the next step is figuring out how when all that redundancy fails how long and how complicated is it to restore from backup. In this case options A and D are the worst in that you need to pull a backup from everything and B and C are superior in that you know what you need to pull. If I did not need the performance from C I would use option B because of the simpler recovery as opposed to option A.

 

I suppose in theory you could also create 4x 2tb duplication pools and then create a single raid 0 array across all of them. In theory that would be the highest possible performance as you would get even higher write speeds but I do not think that the underline duplication pool would work if you did it this way.

 

Lastly, you are 100% correct that anything like option C and D are completely insane for a normal file server where read speeds are not an issue especially if your only on a 1gb/s network.

 

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You can definitely do it that way, especially if your safeguard is to have a backup HDD overnighted to you.  Personally I'd throw a little bit more storage at it and enable either 3x or 4x duplication on a single pool (or have 2x on the master pool and 2x on each child pool).  That would give the redundancy and even better speed for the 10G network, but cost slightly more.  It would also almost negate the need for overnighting a drive in case of ~2 drive failures.

For your scenario (now that I see it and your contingencies better), software RAID snapshots are entirely too slow.  It sounds like your storage solution has far too much turnover (dynamically changing data) for that to work well, and even the creator of SnapRAID indicates it's made more for data repositories that don't change a lot.  So yeah - stick with a pooled solution and redundancy.

Sounds like you've worked out some good solutions and have a fair knowledge of how to achieve your goal, just need to determine what resources ($$) you're going to throw at it and how you want to configure it.  I recently (weeks ago) put together a 88TB server with 72TB of data storage (the remainder for parity).  I sourced the drives in USB enclosures at reduced cost and "shucked" them so I ended up with the bare drives which went into the enclosure.  That might be advantageous for you if you wanted to crank up the duplication in Drivepool - you'd have the space to spare in that case.

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Did a little digging and I can confirm that Backblaze will work with Drivepool.  @Christopher (Drashna) tested it a few years ago.

 

Drivepool actually just passes regular drive commands to the drives, and they are fully portable.  You can shut down, disconnect, and take one to another machine to read the files without any problems.  Having said that - if you run Backblaze against the pool drives (and not the virtual Pool drive itself), you'll be able to have a replacement drive with data sent out to you at need.

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AFAIK, the SSD Optimizer requires a number of SSDs that is equal to the level of duplication. I.e., one SSD will not work for a Pool that has x2 duplication. Having said that, you could create two x2 duplication Pools and put one on top of that, unduplicated and with the SSD as cache. That would work I think.

You have 8x 2tb drives separated into 4 pools of 2 drives each where each pool has duplication. You configure backups to run on each of these individual pools. You then join these 4 pools into 1 large storage pool. You know that the data on each of the 4 smaller pools are exact copies of each other so now when 2 drives fail in a scenario that created data loss you can simply download the 2tb recovery of that individual pool.

I actually think may not work fully unless the backups made are instant. The reason for this is that you may have run a backup at T=0, DP may rebalance at T=1, your drives of one pool may fail at T=2. At T=1, some files may have been written to the failing drives and you would not know it and these would not be available in the backup made at T=0.

This may seem similar to the (normal) loss of data created between backups but this is in fact a bit worse. I may be wrong though.

Now two HDDs failing at the same time is rather rare but you could consider to use CloudDrive as well. You would have either x2 or x3 duplication, depending on how OCD you are and then backups to e.g. Backblaze (which I assume allows for versioning and history). Should you consider CloudDrive then I advise to ask here what the best providers are as some have all kinds of limits/issues (I do not know, not a CloudDrive user).

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7 hours ago, Umfriend said:

AFAIK, the SSD Optimizer requires a number of SSDs that is equal to the level of duplication. I.e., one SSD will not work for a Pool that has x2 duplication. Having said that, you could create two x2 duplication Pools and put one on top of that, unduplicated and with the SSD as cache. That would work I think.

 

I actually think may not work fully unless the backups made are instant. The reason for this is that you may have run a backup at T=0, DP may rebalance at T=1, your drives of one pool may fail at T=2. At T=1, some files may have been written to the failing drives and you would not know it and these would not be available in the backup made at T=0.

This may seem similar to the (normal) loss of data created between backups but this is in fact a bit worse. I may be wrong though.

Now two HDDs failing at the same time is rather rare but you could consider to use CloudDrive as well. You would have either x2 or x3 duplication, depending on how OCD you are and then backups to e.g. Backblaze (which I assume allows for versioning and history). Should you consider CloudDrive then I advise to ask here what the best providers are as some have all kinds of limits/issues (I do not know, not a CloudDrive user).

Ah that is a good point about rebalances! I did not even consider that! Perfect example of why I am double checking my understanding of all of this.

Is there perhaps any log of when these rebalances occur. If this is the case if you had data loss you could simply check the log and see that there was a reblanace since the last backup state and if so then you need to run a full restore instead.

A possibly better solution would be if there is a way to control how the balancing works. For example I have DrivePool configured so that data is evenly distributed on drives based on their capacity %. However, I configure it to never move files that are already placed. So if I delete some files it will be out of balance and stay out of balance until I put some new files in the system. At this time those new files would logically be placed first on the drive that is lower than the others. So I guess the question is if it is possible to completely disable rebalencing and have the balancing only take place when your adding files to the pool.

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1 hour ago, zeroibis said:

So I guess the question is if it is possible to completely disable rebalencing and have the balancing only take place when your adding files to the pool.

 

Yep, that's how I have mine configured currently.  No rebalance passes (unless I kick them off), but native balancing when new files are added.

 

Quote

... by default, StableBit DrivePool adds new data to the drive with the most available free space (absolute, not percentage).

 

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53 minutes ago, Jaga said:

 

Yep, that's how I have mine configured currently.  No rebalance passes (unless I kick them off), but native balancing when new files are added.

 

 

Ah very good to know, that setting eliminates the issue!

 

1 minute ago, Jaga said:

 

You're right, good catch.  Click the up/right arrow below to read the specific reply from Christopher about using the SSD optimizer plugin with duplication.

 

 

I read this to mean that the SSD won't hold multiple copies - one (or more depending on duplication) will end up on mechanical drives in the pool.  But due to the way Drivepool weighs reads from duplication drives, it'll usually choose the SSD for reading at that point.


Good to know and also another reason just to use Primocache instead and just avoid any complication.

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9 hours ago, Umfriend said:

AFAIK, the SSD Optimizer requires a number of SSDs that is equal to the level of duplication. I.e., one SSD will not work for a Pool that has x2 duplication. Having said that, you could create two x2 duplication Pools and put one on top of that, unduplicated and with the SSD as cache. That would work I think.

 

You're right, good catch.  Click the up/right arrow below to read the specific reply from Christopher about using the SSD optimizer plugin with duplication.

 

 

I read this to mean that the SSD won't hold multiple copies - one (or more depending on duplication) will end up on mechanical drives in the pool.  But due to the way Drivepool weighs reads from duplication drives, it'll usually choose the SSD for reading at that point.

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3 minutes ago, zeroibis said:

Ah very good to know, that setting eliminates the issue!

Good to know and also another reason just to use Primocache instead and just avoid any complication.

Yep, the SSD Optimizer definitely has it's place, but it was originally added as a feature request and isn't quite as robust as a separate product designed for full-volume block-level caching (which is also paid software).

You still might run into timing issues with files being added and your backups, but you can control all of that so you'll figure out a good schedule.

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Just for those who happen across this thread I decided to include a diagram of option C from my earlier post.

This is an I/O logic map of using 8 drives which are paired off into RAID 0 arrays and then paired off into Duplication pools and then paired off into a resultant drive pool with PrimoCache being used for a SSD write cache. The advantages of this system is that in the event of data loss you only need to restore data from your backup of the given Duplication pool that experienced a failure instead of the entire drive pool. You also get the performance benefits of the raid 0 array.

DrivePool IO Logic.png

 

Additionally you can improve reliability at the hardware level with the following logic:

Raid 0 Array A can not use drives which are connected to the same controller and or PSU/PSU line as Raid 0 Array B.

Raid 0 Array C can not use drives which are connected to the same controller and or PSU/PSU line as Raid 0 Array D.

This would make the resultant pool immune to a failure resulting from the controller or the PSU/PSU line.

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Not sure if you'd considered it yet, but with your level of interest in reliability and redundancy you may want to run Stablebit Scanner on the same server as Drivepool.  I rely on it now as a "drive watchdog" to email/text me when a disk is starting to have issues, or looks like it might.  It can automatically trigger Drivepool to evacuate a disk's data to others when it senses trouble, and has configurable surface scan checks.  The only caveat to using it is that you couldn't use RAID, since it would obfuscate the drives and not allow Scanner to do it's thing (no SMART data passed with RAID).

Going to try a comparison of your "Solution C" to a standard 8-Drive Pool (both with 2x pool duplication) configured just to see how it comes out with drives dying at the same time.  Feel free to let me know if I miss anything.

 

Failure scenario:  1 drive dying

  • Impact on Solution C:  No Scanner monitoring, so no warning until drive dies.  Takes out 1 volume in a Duplication pool.  Zero data loss or impact on availability.
  • Impact on 8-Drive Pool:  Smart monitoring through Scanner - alerts issued before drive dies.  Drive contents can be auto evacuated to any of the other 7 drives in the pool.  Zero data loss or impact on availability.

Failure scenario:  2 drives dying  (simultaneously)

  • Impact on Solution C:  No Scanner monitoring, so no warning until drive dies or data is damaged.  Potential to take out 50% of all data (one entire Duplication pool).
  • Impact on 8-Drive Pool:  Smart monitoring through Scanner - alerts issued before drives die.   Contents of both drives can be auto evacuated to any of the other 6 drives in the pool.  Potential to take out only 25% of all data - pool duplication and random file distribution reduces this further.

Failure Scenario:  3 drives dying  (simultaneously)

  • Impact on Solution C:  Same impact as 2 drives dying (potential 50% data loss).  Potential for zero file redundancy after failures.
  • Impact on 8-Drive Pool:  Potential to take out ~37% of all data - 2x pool duplication and random file distribution reduces this further.

Failure Scenario:  4 drives dying  (simultaneously)

  • Impact on Solution C:  Potential to take out entire data set (100% failure and 0% availability)
  • Impact on 8-Drive Pool:  Potential to take out ~50% of all data - 2x pool duplication and random file distribution reduces this further.

 

RAID 0 (Solution C) Advantages

  • Read speed increases at the lowest level (drive pairs) in addition to duplication read speed gains.
  • Due to being more highly structured in architecture, hardware level redundancy is increased.

8-Drive Pool Advantages

  • Simple implementation - just add /remove disks to suit storage/duplication desired.
  • Very flexible pool duplication rules - 3x, 4x, etc all available by changing one setting.
  • Able to pass SMART drive data to a monitoring utility like Stablebit Scanner.
  • Able to use file placement rules to populate a specific drive with desired files.
  • Restoring a backup only requires the data on the failed disks be restored (if even necessary - auto-evacuation may have solved the issue with no restore needed).

 

RAID 0 (Solution C) Disadvantages

  • 1 failure takes out data from two paired disks, effectively taking them both offline.
  • 50% drive failure has potential for 0% availability.
  • Requires a more highly structured implementation.
  • Not expandable on a per-drive basis using RAID 0 (Solution C would require expansion by adding 2 more drives all at the same time, 4 if you wanted symmetry).
  • A drive from a RAID 0 pair is not portable, unlike an 8-Drive Pool's drives are.
  • Restoring a backup to a Duplication Pool means 4 drive's worth of data to write.

8-Drive Pool Disadvantages

  • Loses the read speed gains of RAID 0 pairs, though it retains duplication read speed gains.

 

Note:  these are all worst-case scenarios to illustrate the resiliency in the different architectures.  There are best case scenarios as well, like a 4-drive failure on the Solution C causing zero impact (only the mirror drives are taken out).  But since we can't rely on that, I went the way I was taught with disaster recovery planning.  :) 

I do like your architecture and planning, but weighing the pros and cons of it all seems to still be in favor of a traditional 8-drive Pool.  Very interested to hear your thoughts on it as well however!

 

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Oh for reference I 100% plan to be running Stablebit Scanner that was one of the major draws of moving away from hardware raid.

Would the scanner still not work when using software raid 0 as the underline drives are still accessible by the system directly?

Also want to point out that with raid 50% of the drives could fail and you lose nothing just like it is possible for 50% of the drives to fail in the duplication pool as seen in attached image.

fail.png

 

Just to verify if I can pull the drive data in a program like CrystalDiskInfo than Stablebit Scanner will work? Because if I create a software raid 1 in diskmanagement I am able to see the underline drives in CrystalDiskInfo and get smart data. I assume the same would be true if I was to create a raid 0 in diskmanagement instead.

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24 minutes ago, zeroibis said:

Would the scanner still not work when using software raid 0 as the underline drives are still accessible by the system directly?

 

I did try to research that one, but came up without a definitive answer.  I know from experience that Scanner has an "unsafe DirectIO" feature you can enable to poll smart and other data from drives/controllers that otherwise wouldn't pass the info (I use it with my LSI 9201-16e).

For Hardware RAID, it depends largely on the controller and it's driver set (I'd assume most won't pass SMART in a RAID scenario properly).  For Software RAID...  it's anyone's guess.  I'm not sure you'd see the same performance gains in a software RAID 0 stripe as you would a hardware stripe, so from that perspective the primary advantage of it is reduced.  This is what I was able to find after a cursory search:

Perhaps @Alex or @Christopher (Drashna) could chime in on whether or not Scanner (and the auto-evacuate feature in DP) work with software-raided drives.

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I agree that the Scaner would not be able to work if you had your drives behind a hardware raid or anything other than an HBA as the smart data is not passed directly to the OS. As a result you are not able to see drives like that under CrystalDiskInfo either.

I think I got some old 1tb drives lying around maybe I could hook them up and see if I can still get SMART data after putting them in software raid 0.

Interesting about your LSI 9201-16e  that you need to have is pass the SMART data. Is that card flashed to IT mode so it bypasses the internal card firmware?

As far as speed goes software raid 0 can be just as fast to even faster than hardware depending on the system. If your using an intel atom your going to be better off with hardware I would suspect. I will be running on a Ryzen 3 1200 which should offer plenty of CPU for simple raid 0 especially on mechanical drives.

 

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1 hour ago, zeroibis said:

Interesting about your LSI 9201-16e  that you need to have is pass the SMART data. Is that card flashed to IT mode so it bypasses the internal card firmware?

As far as speed goes software raid 0 can be just as fast to even faster than hardware depending on the system. If your using an intel atom your going to be better off with hardware I would suspect. I will be running on a Ryzen 3 1200 which should offer plenty of CPU for simple raid 0 especially on mechanical drives.

 

Yep, using the latest 20.x in IT mode.  It operates in HBA mode fine, just doesn't want to pass SMART without that feature enabled in Scanner.

Interesting about software RAID 0 speeds, I may test that at some point myself just out of curiosity.  It used to be that hardware implementations bypassed all types of other necessary layers, hence were faster.

 

21 minutes ago, Umfriend said:

Wow. The notion of DrivePool not ever balancing except by selecting the appropriate disk for new files is, given my circumstances, ffing brilliant!  How do you ensure DP will never rebalance (unless by user intervention)?

Just disable balancing on the pool - choose "Do not balance automatically", and make sure (if you installed it) that the "Disk Space Equalizer" plugin is turned off (it's usually on-demand anyway for immediate re-balancing).  I also reduce the Automatic Balancing Triggers to around 50% for ratio, and disable "Or if at least this much data needs to be moved" (though it's redundant since Balancing is off except for plugins forcing it).  The only Balancing plugin I have activated actually, is Stablebit Scanner's, for auto-evacuation.  The only maintenance I do regularly on the data, is a simple defragmentation with Auslogics, so that file read speeds stay high.

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1 hour ago, zeroibis said:

Also want to point out that with raid 50% of the drives could fail and you lose nothing just like it is possible for 50% of the drives to fail in the duplication pool as seen in attached image.

-snip-

Just to verify if I can pull the drive data in a program like CrystalDiskInfo than Stablebit Scanner will work? Because if I create a software raid 1 in diskmanagement I am able to see the underline drives in CrystalDiskInfo and get smart data. I assume the same would be true if I was to create a raid 0 in diskmanagement instead.

Yeah, I mentioned that in one of my edits - where it has Note: near the end.  It'd be very rare, though possible.  :) 

Scanner has a free trial period - since you have the software RAID 0 in place, you could install and test.  You wouldn't need (and couldn't use) evacuation in that case since it was a 2x duplicated pool, though I find that feature of Scanner highly valuable, and in your case you could implement it with three 2-pair drives in each Duplication pool (12 total drives).  At the least, you could see if SMART data was being retrieved by Scanner successfully.

Very few (1 or 2?) SMART polling utilities were able to "see through" my LSI controller to the SMART info.  I think they really wanted people to be using the MegaRaid software they developed for it instead.

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