[zfs-discuss] One RAID0 disks for ZFS

Gregor Kopka (@zfs-discuss) zfs-discuss at kopka.net
Wed Apr 18 03:45:36 EDT 2018

Am 18.04.2018 um 09:01 schrieb Makrand via zfs-discuss:
> I am setting up zfs on centos on pretty old server HP Proliant DL580.
> This server has two P400 Raid Controllers each having 8 SAS disks
> behind them. 
> These raid controller can't be set in passthrough mode from BIOS.
> Hence I can't present SAS disks to ZFS as is (as JBOD). I can create
> raid0 logical drive with one disk each and zfs can detect each disk as
> is then. 
> Will it work if I create 8 raid0 drives and then feed them to zfs for
> mirror creation etc?
Yes, this is the best plan for ZFS on controllers that can't expose the
drives as JBOD.

> I am just wondering if that will affect ZFS capability to detect
> faulty drives down the line. Any other cons/negatives this method
> might have?
Con is that you'll possibly have to reboot the system in case of a drive
failure as of the need to make a trip through the controller BIOS to
replace the drive (creating a new raid0 with the new drive to make the
new physical disk visible to the OS) - you should test that scenario so
you'll know upfront.
Apart from that you should make sure the the controller dosn't lie about
write caching/barriers (google might help you on that).

>From what I have read on the internet about them: people suggest to
discard these controllers and replace them with something sane, they
only seem to work in certain HP systems (in others they don't seem to
boot at all or have no way to access their BIOS) - which might lead to
problems accessing the data in case the controller or the server
mainboard dies and you don't have a spare at hand.
No issues should you just want to extend the lifetime of that system and
have remote backups (which you should have anyway).


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