[Top] [All Lists]

Re: Questions on RAID alignment

To: Spelic <spelic@xxxxxxxxxxxxx>
Subject: Re: Questions on RAID alignment
From: Emmanuel Florac <eflorac@xxxxxxxxxxxxxx>
Date: Thu, 20 Sep 2012 14:05:37 +0200
Cc: xfs@xxxxxxxxxxx
In-reply-to: <505AF9EA.7030603@xxxxxxxxxxxxx>
Organization: Intellique
References: <505AF9EA.7030603@xxxxxxxxxxxxx>
Le Thu, 20 Sep 2012 13:11:38 +0200
Spelic <spelic@xxxxxxxxxxxxx> écrivait:

> 1- Does XFS support alignment to concatenation RAIDs (e.g. linear
> over raid1) similarly to striped ones? I am guessing probably su and
> sw should not be specified and the agcount should be multiple of the
> number of the concatenated devices, is that correct?

No, it's better to set your sw/su accordingly to your RAID setup
(example: 8 drives RAID-10 256k stripe -> su=256k,sw=4) and let
mkfs.xfs determine itself how many ag it wants, to adapt it both to the
striping and filesystem size. 

> 2- Can mkfs parameters be altered after creation, e.g. after growing
> a RAID and then growing the XFS fs, can I also alter su, sw, agcount
> somehow?

agcount will be adjusted by xfs_growfs AFAIK. For the other parameters,
not so much.
> 3- I seem to remember there was an xattr that one could attach
> to /home (if /home was under XFS) so that every user (subdir
> of /home) would get a different AG in a different RAID device. I
> cannot find that information anymore on the internet; could you
> refresh my mind?

I really have no idea on this.

Emmanuel Florac     |   Direction technique
                    |   Intellique
                    |   <eflorac@xxxxxxxxxxxxxx>
                    |   +33 1 78 94 84 02

<Prev in Thread] Current Thread [Next in Thread>