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

From: Stan Hoeppner <stan@hardwarefreak.com>
To: Brian Foster <bfoster@redhat.com>
Cc: Eric Sandeen <sandeen@redhat.com>,
	Eric Sandeen <sandeen@sandeen.net>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH 1/2] xfsprogs: ignore stripe geom if sunit or swidth == physical sector size
Date: Thu, 30 Oct 2014 14:15:16 -0500	[thread overview]
Message-ID: <54528E44.5090406@hardwarefreak.com> (raw)
In-Reply-To: <20141030114605.GA5914@bfoster.bfoster>

On 10/30/2014 06:46 AM, Brian Foster wrote:
> 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:

It's a dm-multipath device.  I pasted details up thread.  Here, again:

# multipath -ll
3600c0ff0003630917954075401000000 dm-0 Tek,DH6554
size=44T features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=50 status=active
| `- 9:0:0:3 sdj 8:144 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
  `- 1:0:0:3 sdf 8:80  active ready running

# blockdev --getpbsz --getss --getiomin --getioopt  /dev/dm-0
512
512
512
1048576

# blockdev --getpbsz --getss --getiomin --getioopt  /dev/sdj
512
512
512
1048576

# blockdev --getpbsz --getss --getiomin --getioopt  /dev/sdf
512
512
512
1048576

Cheers,
Stan

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