On Tuesday, April 21, 2020 at 8:20:23 AM UTC-7, Robert ECEO Townley wrote: > > Wondering myself. > > On Apr 21, 2020, at 2:31 AM, Gionatan Danti <[email protected]> > wrote: > > > [reposting, as the previous one seems to be lost] > > Hi all, > I have a question regarding udev events when using iscsi disks. > > By using "udevadm monitor" I can see that events are generated when I > login and logout from an iscsi portal/resource, creating/destroying the > relative links under /dev/ > > > So running “udevadm monitor” on the initiator, you can see when a block > device becomes available locally. > > > > However, I can not see anything when the remote machine simple > dies/reboots/disconnects: while "dmesg" shows the iscsi timeout expiring, I > don't see anything about a removed disk (and the links under /dev/ remains > unaltered, indeed). At the same time, when the remote machine and disk > become available again, no reconnection events happen. > > > As someone who has had an inordinate amount of experience with the iSCSi > connection breaking ( power outage, Network switch dies, wrong ethernet > cable pulled, the target server machine hardware crashes, ...) in the > middle of production, the more info the better. Udev event triggers would > help. I wonder exactly how XenServer handles this as it itself seemed > more resilient. > > XenServer host initiators do something correct to recover and wonder how > that compares to the normal iSCSi initiator. >
I was under the impression that XenServer used open-iscsi. > > But unfortunately, XenServer LVM-over-iSCSi does not pass the message > along to its Linux virtual drives and VMs in the same way as Windows VMs. > > > When the target drives became available again, MS Windows virtual > machines would gracefully recover on their own. All Linux VM > filesystems went read only and those VM machines required forceful > rebooting. mount remount would not work. > A filesystem going read-only means it was likely ext3, which does that if it gets IO errors, I believe. (Disclaimer: I'm not a filesystem person.) > > > -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/open-iscsi/a3ff8e76-fa9b-4290-ba20-f3bf43989b66%40googlegroups.com.
