Newbie - if I have 8 HDDs and 4X mirroring, and one drive fails, will DrivePool automatically use another disk to continue 4X mirroring?

[Kindrox]

I apologize if the answer to the question is somehow right in my face but I used the search tool and didn't see it.

I work in a legal setting with client litigation files. The consequences to losing the files are very high, so I created a pool of 8 hard drives and 4X mirroring.

I know 4 of the 8 failing in a short amount of time is probably never going to happen, but suppose the data is spread equally over the 8 drives and one fails.  Will DP automatically start copying data between the now 7 drives to maintain the 4X mirroring of all the files?  One answer I read suggested that might not happen until/unless the bad drive is removed from the pool or replaced.

I travel some (so in theory this could happen while I am not there to do something about it) and it would be nice to know if DP is bullet proof in this regard.

[marquis6461]

At one point in time I had the same configuration.  In my case the answer was YES.  When the one drive failed, I was able to remove it and my pool saw NO lose of data.  A little rebalancing was required but in the overall situation nothing was lost.  I would suggest you keep the Mirror and multiple duplication on JBODs.  A NAS can lose a little if multiple disks fail because of power bounces but if you keep a UPS online with the protections you will be fine.

[Shane]

Hi Kindrox!

As a general note I would make sure that "Real-time duplication" is checked under Manage Pool -> Performance. This is to immediately duplicate files placed in the pool rather than nightly. (I would also un-tick "Read striping" in the same section as stability is more important than performance and some people have reported problems with some apps when read striping is enabled).

"One answer I read suggested that might not happen until/unless the bad drive is removed from the pool or replaced."

If a disk in the pool goes missing (e.g. from power loss, cable disconnect or a sudden total failure):

• the pool automatically enters a read-only state until the disk is returned to or removed from the pool (users will not be able to save files until that happens), to protect the pool's organisational structure during temporary disk absences.
• if your business requires 24/7 writeability even in your absence, you could consider:
  • setting up some form of secure remote access so you can remove a missing disk even while away,
  • and/or using another method besides DrivePool, either in addition (e.g. hardware RAID cards, QNAP/Synology DAS boxes, etc) or instead (e.g. TrueNAS OS, UnRaid OS, OMV OS, QNAP/Synology NAS boxes, etc). These can also offer parity protection for protection against bit damage.

If a disk in the pool goes bad (e.g. from bad sectors or mechanical problems):

• the internal SMART diagnostics should flag the problem; if you also have StableBit Scanner installed and the Scanner balancer enabled in DrivePool, the two will work together and you can set the balancer to automatically evacuate files from bad disks (and if you have Nx duplication it will attempt to move files as necessary to Nx good disks in the pool).
• the pool will attempt to remain both readable and writable while this happens.

Please note that DrivePool is a RAID1-like software, so the applicable IT adage is "RAID is not backup". A deleted or damaged file remains a deleted or damaged file. Always have a backup strategy (e.g. one 'best practice' approach I'm familiar with is "always maintain at least 3 independent instances in at least 2 storage types with at least 1 off-site in case the building burns down") that is appropriate to your level of need (and liability).

[Kindrox]

Thanks folks!  I just turned Read Striping off, and real time duplication was already enabled.

It is just me accessing the drive right now, so fortunately I don't have to do anything other than not lose the data. I don't know very much about bit damage, is this a serious concern?  You might need to know more about my application.

I am storing evidence for clients. The majority of the used disk space is taken up by videos. Nearly always files get written to the pool once, and then remain unchanged and would only be read back.  My backup is saving the whole drive to a rotating set of other hard drives.

I'll get the scanner app too.

[marquis6461]

I found this drive on amazon.  I ordered it.  I haven't gotten it yet but if it is true then it will be the backup service I am looking for and also for you.

I would suggest getting 2 and try them.  I am using filesync in update mode.  This allows a history of all the files to be saved. The one option I do love is the trashcan mode.

When everything is up to date, your system will flag deleted files from your main system as missing.  After a period of 6 months, it will delete it from the backup after giving you notice. There has been many times, I had to look back in the trash for something I overlooked.  You also have the option to archive it but I found that can be quite a task to clean up and loses real hard drive space.  I tried the DVD archive mode and was dissappointed.  The backups did not stick right and when I needed them they took too long to recover or were so hard to read it wasted a lot of time.

 

https://www.amazon.com/Seagate-Expansion-22TB-External-Drive/dp/B0DW8ZW47C/ref=sr_1_1_sspa?

 

Hope this helps with your storage issue and backup. Every I.T. specialist in the world will talk a good game until disaster strikes.

My suggestion to you is this.

Buy the drives.  Place them on a U.P.S. with a little used computer or laptop running the filesync program. Have it backup your Drivepool 1 time. Test the backup to see if you can copy some files FROM the backup to review without restoring the whole thing. It will save you a lot of Tums and time.  You can do like I do on my backup right now.  I do a search for the directory I want and I can review the files in less than 5 minutes.  Don't fall for cloud service or any backup software you can't control.  Above all, ( I learned this the hard way) doe't encrypt your backup or compress it trying to save space. If you need to, lock the backup up and only connect once a week.

Hope this helps with your situation.  Mine was pretty much the same but I had to keep track of the Navy Tool System. We had a mess when new replaced old. I was thankfull I still kept my card file as backup.

[Kindrox]

Thank you!