Swap HDD (add new, remove old) - Some Feedback

[jmone]

Some Feedback on the Drive Add / Remove / Swap use case for me.

 

As my Pool Fills up, I remove the oldest drive (say 4TB) and replace with a bigger drive (say 8TB) due to lack of ports on one of my Pools.  In DriveBender you could 'swap drives' and it was nice and fast.  DrivePool on the other hand uses the Balancer which is slow and tends to first move the files to your SSD (if you have one) not the new drive (which then filled it up and the process stopped).  I've been reading and playing with a few of the settings and work arounds but it all takes a long time and is harder than it should be.  I just want to swap the drives as fast as possible then let the balancer do its thing over time. 

 

Looking forward to when the dev of this part makes this part work.

 

Thanks

Nathan

[Spider99]

whats slow, fast and long by your definition?

[jmone]

Fast is anything approaching raw disk copy speed, and I think DrivePool does a pretty good job of approaching this when reading / writing to the pool for foreground processes.  

 

When copy large files (It is worth noting that the raw speed difference is considerable between large and small files and physical placement on the platters, type and mix of HDD etc) between my pools I can hit 130MB/sec but on average I would say I get 90MB/Sec on mixed files, or about 315GB per hour (this is between two Hitachi 4TB 7,200rpm drives I've set as SSD on each pool).  

 

According to Drashna the Balancing Engine uses background processes and he states that takes "longer" than what you can get if you stop the DrivePool process and copy the files manually.  I certainly see this on my system as it currently moving the large (multi GB) files at around 45MB/Sec or about 160GB per hour, and an average closer to 35MB/Sec or about 125GB per hour on mixed files.... so about half the throughput at best (note: this is also copying from a Hitachi to a Seagate 8TB Archive which are slower on sustained writes which complicates the comparison!!) 

[Shane]

It almost sounds as if you're saying you're relying on the Balancer to remove the files from the old drive rather than using the Remove button?

 

If you mean that the Remove process is still using the engine and thus being slowed that way - have you tried turning off Automatic balancing before starting the Removal process, ticking "Duplicate files later", and/or setting a global file replacement rule to prioritise the new drive above all others?

[jmone]

At first I used the remove button but it failed with a msg about no avail disk space after it filled up some free space from one of the other drives and did not put anything on the new 8TB HDD in the pool.  So after reading some posts I'm using the Balancer.  I've only 300GB to go so I'll let it run (+ I'm now away with work for a few days).  When I'm back I'll then "remove" the hopefully empty drive and reset the Balancer to they way it was.

[Shane]

Very odd; DrivePool's default rule is to move/copy files to whichever drive(s) have the most free space, except as otherwise instructed by custom balance/placement rules. If you still can't remove the old drive via its button when you get back and can't find anything at fault in a custom rule, I'd suggest filing a support request via https://stablebit.com/Contact

[Spider99]

have you tried increasing the priority of the balancing task?

[Christopher (Drashna)]

If you want to just "swap" drives, and all the content on it is duplicated, you can use the "duplicate data later" option when removing the drive. This skips over the duplicated data and then reduplicates it later. 

 

At this point, pull the old drive, put in the new one, add it to the pool, and mostly done.  Depending on what version you're using, you may see a ">>" icon next to the pool condition bar at the bottom. Click on this to increase the duplication pass priority. This should boost the priority to a more normal speed. 

 

 

You can also do this permanently: 

http://stablebit.com/Support/DrivePool/2.X/Manual?Section=Balancing%20Settings

[jmone]

Thanks - It's all done and working fine.  I'll be doing more swaps soonish as I upgrade another 4tb drive to 8tb.  I don't use duplication on the pool (I have another pool on another server that a use to Backup this pool from).

 

FYI my use case is pretty simple:

- For BD Rips use the 8TB Seagate Archive Drives and fill them up one at a time and in order

- For other items (video editing, VM images, prog files etc) use the 4TB Hitachi 7200 drives

- I've even turned off the SSD option

- Once or week or so I do a compare with the 2nd backup pool on the other server (using FreeFileSync) before committing any changes to this pool (in case of accidental deletes etc).