Public bug reported:
Hello everyone, I'm a little confused about the behavior of libvirt in
Ubuntu 16.04.3.
We have up to 140 iSCSI targets on a single storage host, and all of
these are made available to our VM hosts. If I stop one of the iSCSI
pools through virsh ("virsh pool-destroy iscsipool1") and start it back
up again while running libvirt in debug, I see that it runs a discovery
and proceeds to go through and update every single target available on
that host -- even targets that we do not use, instead of simply
connecting to that target.
This turns a <1 second process into a minimum of 30 seconds, and I just
ran it with the stopwatch and clocked it at 64 seconds. So if we are
doing maintenance on these hosts and go for a reboot, it takes 90-120+
minutes to finish auto starting all of the iSCSI pools. And of course,
during this period of time, the server is completely worthless as a VM
host. Libvirt is just stuck until it finishes connecting everything.
Manually connecting to the targets using iscsiadm without doing all the
same hubbub that libvirt is doing connects these targets immediately, as
I would expect from libvirt.
And for each of the 140 iSCSI targets, it goes through and runs an
iscsiadm sendtargets and then updates every single target before finally
connecting the respective pool.
We also noticed that libvirt in Ubuntu 17.10 does not have this
behavior. Well maybe it does, but it connects the iSCSI targets
immediately. It is a much different process than Ubuntu 16.04.3.
Any help would be greatly appreciated. Thank you so much.
** Affects: libvirt (Ubuntu)
Importance: Undecided
Status: New
** Tags: iscsi storage
** Tags added: iscsi
** Tags added: storage
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https://bugs.launchpad.net/bugs/1738864
Title:
libvirt updates all iSCSI targets from host each time a pool is
started
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