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RAIDZ2 with 4 drives running with only 2

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Joined: 12 Jul 2018 21:15
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RAIDZ2 with 4 drives running with only 2


Post by testmaster »


Maybe this is a "basic" question, but I can't figure out the answer.

So first off all, I'm testing this in an virtual machine.
Only testing of course.
(Because it's easier to simulate power failer, HDD-Crashes, remove the HDD when resilvering/copying new data on it and so on, without that I harm my hardware)

So I createt a new RAIDZ2 Pool with 4 drives.
Then I put some data on it.
After that I shutded down the machine, and reboot only with 2 drives of the 4 from the RAIDZ2 Pool.
As expected, the pool shows up in degraded state - all data OK - Good
(No new data was added)
So then I reboot another time, but now with all "original" 4 drives.
Then zpool shows me on minimum one drive that was detached in the "previouse step" has Checksum-Errors, but why?

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Re: RAIDZ2 with 4 drives running with only 2


Post by Maurizio »

Because some data was written to the two disks. You can use the command:

Code: Select all

# zpool iostat -v
it displays I/O statistics for the pools and see if something was written to the pools.
XigmaNAS on Dell R710 144GB RAM - RootOnZFS zroot on 2x 64GB 15k HDDs in mirror, zdata on 3x 1TB SSD in RAIDZ1.
2x XigmaNAS - RootOnZFS on HPE Proliant Microserver gen10 X3216 - 3x 4TB WD RED. In mirror with zrep.

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