Zpool two failed devices - is it lost?

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imperimus

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Hi Folks,

Probably a simple one. I have had two disks fail and it seems that both of those disks were in use by a zpool. If i try to import the zpool it complains about the missing parts (see screen shot attached). I can recreate the VMs i had running on this but just wanted to check whether there was anything else I could try first, before I go to all that effort?

Many thanks in advance!
 

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HoneyBadger

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Two disks dead in a RAIDZ1 is "Game over", sorry. You might be able to force import but the likelihood of salvaging data is pretty low.

But since you're rebuilding anyways - use mirror vdevs for your new pool if you're putting VMs on them. Significantly better random I/O performance.

And if Volume-1 is also a 14-disk RAIDZ1 (yikes) you should try to move the data off of it and recreate with smaller vdevs.

Welcome, and sorry your first post doesn't have a happy answer.
 

imperimus

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Thanks for the prompt response. Thought it was the case but always worth checking. Still think it think it is a fantastic product, and it is just a reminder to set up the email alerts so I notice when the first disk goes and not the second!

But since you're rebuilding anyways - use mirror vdevs for your new pool if you're putting VMs on them. Significantly better random I/O performance.

Although I have built a few FreeNAS setups ( I am still only learning) I use Z2 as performance isn't of overall importance in my test infrastructure as I generally run out of space first. But as you mention it with 15 disks in a shelf would it be within the recommendations to build a volume using with 7x2x300GB Mirrors with 1 hot spare?
 

gpsguy

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Yes.

Note: - "If you are using iSCSI, it is recommended to not let the pool go over 50% capacity to prevent fragmentation issues."

But as you mention it with 15 disks in a shelf would it be within the recommendations to build a volume using with 7x2x300GB Mirrors with 1 hot spare?
 

HoneyBadger

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Although I have built a few FreeNAS setups ( I am still only learning) I use Z2 as performance isn't of overall importance in my test infrastructure as I generally run out of space first. But as you mention it with 15 disks in a shelf would it be within the recommendations to build a volume using with 7x2x300GB Mirrors with 1 hot spare?

Since you're still in a testing phase it would be an ideal time to set up one pool as Z2 and one pool as mirrors in order to compare throughput. IOPS in a zpool scales with the number of vdevs, so a 7x2 mirror will have 7x the IOPS of a single 15-disk RAIDZ2.
 
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