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
>> 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?
> This seems reasonable to me and the code looks fine, save a trailing
> whitespace instance below.
Doh! >:( ;) thanks.
> I'm just curious if there are any weird
> corner cases where there's value in the reported optimal I/O size or the
> real world situation was just noise.
yeah, hard to know - How *would* you use it?