[zfs-discuss] Linux IO Target: iSCSI LUN with 4 KB blocksize

kaazoo kaazoo at kernelpanik.net
Thu Jan 14 08:47:23 EST 2016


Am 08.01.16 um 16:34 schrieb kaazoo via zfs-discuss:
> 
> Why is a physical blocksize of 32 KB instead of 4 KB reported?
> Is this a bug in LIO or a configuration issue?
> 
> Another strange thing is that the HW blocksize of the zvol is reported
> as 512 byte:
> /backstores/iblock/iscsi> get attribute hw_block_size
> hw_block_size=512 [ro]
> 


This appears to be an issue with LIO. You can overwrite the logical
blocksize, but it will choose a physical blocksize on its own, which
doesn't make sense to me.

When using the SCST target implementation, you can overwrite logical and
physical blocksize at the same time with the configuration parameter
"blocksize 4096" no matter what the real blocksize of the underlying
device is.

As a side note, there are Ubuntu PPAs for SCST 3.0 and 3.1 at
https://launchpad.net/~scst .


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