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Re: [PATCH 1/2] xfsprogs: ignore stripe geom if sunit or swidth == physi

To: Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>
Subject: Re: [PATCH 1/2] xfsprogs: ignore stripe geom if sunit or swidth == physical sector size
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Thu, 30 Oct 2014 07:46:05 -0400
Cc: Eric Sandeen <sandeen@xxxxxxxxxxx>, Eric Sandeen <sandeen@xxxxxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <54515E4E.8010500@xxxxxxxxxxxxxxxxx>
References: <544FD3E1.1060000@xxxxxxxxxx> <20141029183721.GA4226@xxxxxxxxxxxxxx> <54513635.7050703@xxxxxxxxxxx> <54515E4E.8010500@xxxxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.23 (2014-03-12)
On Wed, Oct 29, 2014 at 04:38:22PM -0500, Stan Hoeppner wrote:
> On 10/29/2014 01:47 PM, Eric Sandeen wrote:
> > On 10/29/14 1:37 PM, Brian Foster wrote:
> >> On Tue, Oct 28, 2014 at 12:35:29PM -0500, Eric Sandeen wrote:
> >>> Today, this geometry:
> >>>
> >>> # modprobe scsi_debug  opt_blks=2048 dev_size_mb=2048
> >>> # blockdev --getpbsz --getss --getiomin --getioopt  /dev/sdd
> >>> 512
> >>> 512
> >>> 512
> >>> 1048576
> >>>
> >>> will result in a warning at mkfs time, like this:
> >>>
> >>> # mkfs.xfs -f -d su=64k,sw=12 -l su=64k /dev/sdd
> >>> mkfs.xfs: Specified data stripe width 1536 is not the same as the volume 
> >>> stripe width 2048
> >>>
> >>> because our geometry discovery thinks it looks like a
> >>> valid striping setup which the commandline is overriding. 
> >>> However, a stripe unit of 512 really isn't indicative of
> >>> a proper stripe geometry.
> >>>
> >>
> >> So the assumption is that the storage reports a non-physical block size
> >> for minimum and optimal I/O sizes for geometry detection. There was a
> >> real world scenario of this, right? Any idea of the configuration
> >> details (e.g., raid layout) that resulted in an increased optimal I/O
> >> size but not minimum I/O size?
> > 
> > Stan?  :)
> 
> Yeah, it was pretty much what you pasted sans the log su, and it was a
> device-mapper device:
> 
> # mkfs.xfs -d su=64k,sw=12 /dev/dm-0
> 

What kind of device is dm-0? I use linear devices regularly and I don't
see any special optimal I/O size reported:

# blockdev --getpbsz --getiomin --getioopt --getbsz /dev/mapper/test-scratch 
512
512
0
4096

Brian

> --
> Stan
> 
> 
> 

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