[ceph-users] Using FC with LIO targets

Mike Christie mchristi at redhat.com
Tue Oct 30 20:59:42 PDT 2018


On 10/28/2018 03:18 AM, Frédéric Nass wrote:
> Hello Mike, Jason,
> 
> Assuming we adapt the current LIO configuration scripts and put QLogic HBAs in our SCSI targets, could we use FC instead of iSCSI as a SCSI transport protocol with LIO ? Would this still work with multipathing and ALUA ?
> Do you see any issues coming from this type of configuration ?

The FC drivers have a similar problem as iscsi.

The general problem is making sure the transport paths are flushed when
we failover/back. I had thought using explicit failover would fix this,
but for vpshere HA type of setups and for the single host with multiple
initiator ports to connected to the same target port we still hit issues.

For iscsi, I am working on this patchset (maybe half is now merged but
the patchset is larger due to some other requested fixes in sort of
related code):

https://www.spinics.net/lists/target-devel/msg16943.html

where from userspace we can flush the iscsi paths when performing
failover so we know there are no stale IOs in that iscsi/code path.

For FC drivers I was planning something similar where we would send a FC
echo like we do for the iscsi nop.

If you are asking if you can just drop in one of the FC target drivers
into the ceph-iscsi-config/cli/tcmu-runner stuff then it would not work,
because there are a lot of places where iscsi references are hard coded now.



> Best regards,
> Frédéric.
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