From: Eric Sandeen <sandeen@sandeen.net>
To: Helmut Tessarek <tessarek@evermeet.cx>, xfs@oss.sgi.com
Subject: Re: How to format RAID1 correctly
Date: Tue, 23 Sep 2014 21:21:24 -0500 [thread overview]
Message-ID: <54222AA4.5010501@sandeen.net> (raw)
In-Reply-To: <5422285B.6010306@evermeet.cx>
On 9/23/14 9:11 PM, Helmut Tessarek wrote:
> On 23.09.14 22:07 , Eric Sandeen wrote:
>> but! your raid doesn't have a 64k stripe, so that doesn't apply.
>
> Yep, that's true, but see below.
>
>> no geometry because md0 raid1 doesn't export any stripe geometry.
>
> [root@atvie01s ~]# cat /proc/mdstat
> Personalities : [raid1]
> md0 : active raid1 sdb1[0] sdd1[1]
> 3906784064 blocks super 1.2 [2/2] [UU]
> bitmap: 0/30 pages [0KB], 65536KB chunk
>
> So for some reason it shows a 64k chunk size even for RAID1.
>
> That was what got me confused.
Hm, 65536KB sounds like 64MB...
Anyway, mkfs.xfs picks up the queue's minimum IO size for
sunit, and optimal io size for swidth.
So:
blkid # blockdev --getiomin --getioopt /dev/md0
(which here returns:
512
0
here)
will show you what your raid's queue is actually reporting,
and what mkfs.xfs will pick up.
-Eric
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next prev parent reply other threads:[~2014-09-24 2:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-24 0:46 How to format RAID1 correctly Helmut Tessarek
2014-09-24 2:05 ` Helmut Tessarek
2014-09-24 2:07 ` Eric Sandeen
2014-09-24 2:11 ` Helmut Tessarek
2014-09-24 2:21 ` Eric Sandeen [this message]
2014-09-24 2:30 ` Helmut Tessarek
2014-09-24 3:05 ` stan hoeppner
2014-09-24 3:15 ` Helmut Tessarek
2014-09-24 4:09 ` Stan Hoeppner
2014-09-24 15:53 ` Helmut Tessarek
2014-09-24 16:18 ` Eric Sandeen
2014-09-24 19:06 ` Stan Hoeppner
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