Storage design - to mirror or not?

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Innocuous

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Nov 4, 2013
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Hi all,

I am thinking of moving away from my old server based on Win 8 towards FreeNas. I have loads of questions but I hope that most can be answered through trawling the forums. There are a few that I cannot seem to find around ZFS and Raid Mirror set-ups.

Questions:
- If I create a raid mirror (raid-1) with ZFS will I still get to take advantage of continuous integrity checking, error checking and auto repair or does this only come when using Raid Z1/2/3 ?
- If I use Raid mirror and my motherboard/PSU etc dies destroying one of the disks at the same time can I still access my data from the good drive using FreeNAS / Ubuntu on a different computer?
- I have heard that data recovery tools are few and far between with ZFS. The only concern I have is if I were to do something stupid like delete a partition table on a drive that I was trying to recover from, are there tools to recover from this sort of issue if I am only using Raid Mirror?
- Based on the info below on my set-up, is ZFS worth it, or should I stick with another file system?

More data on my current set-up and requirements is below.

Thanks for your help.

Current Server Set-up:
Tier 1 Storage - Essential Data (Files, Photos, Music)
- 1 TB of data
- 1TB drive with nightly backup to another 1TB drive in the same box every night (not a great solution, but reduces the risk that both disks fail at the same time and reduces wear on 2nd drive)
- Auto sync to my primary workstation daily
- CrashPlan backup enabled

Tier 2 Storage - Normal Data (Video Media)
- 5TB of storage
- 3 TB drive with nightly backup to another 3TB drive
- 2TB drive with nightly backup to another 2 TB drive

(One reason for moving away from Windows is slow transfer speeds, I guess Raid Mirror for these drives would give me a super quick data access?)

Tier 3 Storage - Working Data (In Process Downloads)
- 0.5TB drive with no backup (if I lose the data I do not care that much)
 

warri

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Jun 6, 2011
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Hi, here are some answers for you.

Hi all,
- If I create a raid mirror (raid-1) with ZFS will I still get to take advantage of continuous integrity checking, error checking and auto repair or does this only come when using Raid Z1/2/3 ?
Yes (assuming you're talking about a ZFS Mirror and not an actual RAID 1).

- If I use Raid mirror and my motherboard/PSU etc dies destroying one of the disks at the same time can I still access my data from the good drive using FreeNAS / Ubuntu on a different computer?
Yes, the pool will run as degraded pool and is importable by any OS supporting your ZFS version.

- I have heard that data recovery tools are few and far between with ZFS. The only concern I have is if I were to do something stupid like delete a partition table on a drive that I was trying to recover from, are there tools to recover from this sort of issue if I am only using Raid Mirror?
Not quite sure. If you delete just the partition table, you probably could recover it from the second disk. No guarantees, though.

- Based on the info below on my set-up, is ZFS worth it, or should I stick with another file system?
I think ZFS makes sense. You would avoid those daily backups to another HDDs by using a ZFS Mirror (although they are not proper backups if they are not off-site) and profit of the integrity and error detection and correction.
But, all those features heavily rely on proper hardware. Many people argue that you should use ECC Ram and server grade hardware, because RAM failures could trash your whole pool and subsequent backups when doing a scrub. There are some topics in this forum which discuss those possibilities.

So, on which hardware are your servers running? Do you just want to use FreeNAS/ZFS for the Tier 1 or all of them?
 

Innocuous

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Nov 4, 2013
Messages
9
Thanks for the in-depth responses - they are really useful and informative. I was thinking of using ZFS for Tier 1 & Tier 2, but I am getting the impression that this might be complete overkill for my needs. Whilst I like the idea of ZFS integrity checking, none of my data is really that important and even the Tier 1 data which is the most critical to me has back-up's on several PC's and on the cloud.

If I were to not use ZFS, is there an alternative within FreeNAS which would give me a straight forward Raid 1 set-up giving me a performance boost without the integrity overhead?
 

warri

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Jun 6, 2011
Messages
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FreeNAS also supports UFS with RAID1.
 
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