|To:||Dave Chinner <david@xxxxxxxxxxxxx>|
|Subject:||Re: xfs hardware RAID alignment over linear lvm|
|From:||Stewart Webb <stew@xxxxxxxxxxxxxxxxxx>|
|Date:||Thu, 26 Sep 2013 09:55:38 +0100|
|Cc:||Chris Murphy <lists@xxxxxxxxxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>|
|References:||<CAE3v2EaODFud_S_BzuSjtwGwuNBXhvL0RiPB1P5QroF45Obwbw@xxxxxxxxxxxxxx> <52435327.9080607@xxxxxxxxxxxxxxxxx> <2F959FD9-EF28-4495-9D0B-59B93D89C820@xxxxxxxxxxxxxxxxx> <20130925215713.GH26872@dastard>|
Thanks for all this info Stan and Dave,
> "Stripe size" is a synonym of XFS sw, which is su * #disks. This is the
> amount of data written across the full RAID stripe (excluding parity).
The reason I stated Stripe size is because in this instance, I have 3ware RAID controllers, which refer to
this value as "Stripe" in their tw_cli software (god bless manufacturers renaming everything)
I do, however, have a follow-on question:
On other systems, I have similar hardware:
3x Raid Controllers
1 of them has 10 disks as RAID 6 that I would like to add to a logical volume
2 of them have 12 disks as a RAID 6 that I would like to add to the same logical volume
All have the same "Stripe" or "Strip Size" of 512 KB
So if I where going to make 3 seperate xfs volumes, I would do the following:
mkfs.xfs -d su=512k sw=8 /dev/sda
mkfs.xfs -d su=512k sw=10 /dev/sdb
mkfs.xfs -d su=512k sw=10 /dev/sdc
I assume, If I where going to bring them all into 1 logical volume, it would be best placed to have the sw value set
to a value that is divisible by both 8 and 10 - in this case 2?
Obviously, this is not an ideal situation, and I will most likely modify the hardware to better suite.
But I'd really like to fully understand this.
Thanks for any insight you are able to give
On 25 September 2013 22:57, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
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