I think I do not understand you completely. How long does a live
migration take? If I do virsh migrate with vm's on librbd it is a few
seconds. I guess this is mainly caused by copying the ram to the other
host.
Any time more this takes in case of a host failure, is related to time
out settings, failure detection and locks being released etc.
-----Original Message-----
From: Mathieu Dupré [mailto:mathieu.dupre@savoirfairelinux.com]
Sent: dinsdag 6 oktober 2020 9:40
To: ceph-users(a)ceph.io
Cc: Bail, Eloi
Subject: [ceph-users] Write access delay after OSD & Mon lost
Hi everybody,
Our need is to do VM failover using an image disk over RBD to avoid data
loss.We want to limit the downtime as much as possible.
We have: - Two hypervisors with a Ceph Monitor and a Ceph OSD. - A third
machine with a Ceph Monitor and a Ceph Manager.
VM are running over qemu.The VM disks are on a "replicated" rbd pool
formed by the two OSDs.Ceph version:
NautilusDistribution: Yocto Zeus
The following test is performed: we electrically turn off one hypervisor
(and therefore a Ceph Monitor and a Ceph OSD), which causes its VMs to
switch to the second hypervisor.
My main issue is that the mount time of a partition in rw is very slow
in the case of a failover (after the loss of an OSD its monitor).
With failover we can write on the device after ~25s:[ 25.609074]
EXT4-fs (vda3): mounted filesystem with ordered data
mode. Opts: (null)
In normal boot we can write on the device after ~4s:[ 3.087412]
EXT4-fs (vda3): mounted filesystem with ordered data
mode. Opts: (null)
I wasn't able to reduce this time by tweaking Ceph settings. I am
wondering if someone could help me on that.
Here is our configuration.
ceph.conf[global] fsid = fa7a17d1-5351-459e-bf0e-07e7edc9a625 mon
initial members =
hypervisor1,hypervisor2,observer mon host =
192.168.217.131,192.168.217.132,192.168.217.133 public network =
192.168.217.0/24 auth cluster required = cephx auth service
required = cephx auth client required =
cephx osd journal size = 1024 osd pool default size = 2 osd
pool default min size = 1 osd crush chooseleaf
type = 1 mon osd adjust heartbeat grace = false mon osd min down
reporters = 1[mon.hypervisor1] host =
hypervisor1 mon addr = 192.168.217.131:6789[mon.hypervisor2] host
= hypervisor2 mon addr =
192.168.217.132:6789[mon.observer] host = observer mon addr =
192.168.217.133:6789[osd.0] host =
hypervisor1 public_addr = 192.168.217.131 cluster_addr =
192.168.217.131[osd.1] host =
hypervisor2 public_addr = 192.168.217.132 cluster_addr =
192.168.217.13
# ceph config dump WHO MASK LEVEL OPTION
VALUE RO global advanced
mon_osd_adjust_down_out_interval false global advanced
mon_osd_adjust_heartbeat_grace false global advanced
mon_osd_down_out_interval 5 global advanced
mon_osd_report_timeout 4 global advanced
osd_beacon_report_interval 1 global advanced
osd_heartbeat_grace 2 global advanced
osd_heartbeat_interval 1 global advanced
osd_mon_ack_timeout 1.000000 global advanced
osd_mon_heartbeat_interval 2 global advanced
osd_mon_report_interval 3
Thanks
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io To unsubscribe send an
email to ceph-users-leave(a)ceph.io