Can someone test zvol expansion with iSCSI?

[kdragon75]

In 11.1U6 if you expand a zvol that is presented as an iSCSI LUN, the new size is not reported until the iSCSI (ctld) service is restarted. Can anyone confirm if this is still the case for 11.2? I know I could test this in a VM but I'm lazy/busy/either.

 

[Ericloewe]

I'm not sure you can even work around this. SCSI devices aren't known to magically change in size during operation, in most cases.

 

[kdragon75]

It seems a fairly normal thing to live grow LUSs. Not to mention growing live virtual disks that are often backed by virtual scsi controllers. All that we would need is to do is on zvol resize, check if its used as an extent in ctld.conf and if it is and ctld is running, gracefully restart reload it or at the least, let give the administrator the option. It's just one of those finishing polish things that FreeNAS could use.

Further reading suggests the prefered way of doing this would be ctladm modify -l <LUN_NUMBER> -s auto <LUN_NUMBER> would be the ctl LUN number and not the iSCSI LUN number. So this is all baked in to ctl/ctladm and just need to be leveraged by FreeNAS. I would think this falls under the input validation/automation subject.

 

[HoneyBadger]

In 11.1U6 if you expand a zvol that is presented as an iSCSI LUN, the new size is not reported until the iSCSI (ctld) service is restarted.

That's a huge regression from 9.10 if so - all I have to do there is expand the ZVOL, do a rescan from the initiator (usually, VMware) and the new capacity is visible.

I'm not sure you can even work around this. SCSI devices aren't known to magically change in size during operation, in most cases.

Physical drives certain aren't known to spontaneously change sizes, but live expansion of LUNs is commonplace.

 

[Ericloewe]

Really? Goes to show how little I've messed around with network block devices - and the stuff consuming them. I always assumed the experience would be about as traumatic as the few times I've done it with VMs and virtual disks.

 

[HoneyBadger]

I always assumed the experience would be about as traumatic as the few times I've done it with VMs and virtual disks.

It is ... which is to say that "it shouldn't be, unless you've done something very wrong."