|
xen-users
Re: [Xen-users] EVMS or GFS
Thank you for your thoughts on this subject. I will try to setup DRDB on
my shared storage and EVMS on my app servers. This way I will keep my
setup as clean as posible regarding patching and maintains.
- Karsten
Javier Guerra wrote:
On Thursday 25 May 2006 11:40 am, Karsten Nielsen wrote:
Is it important to use a cluster-aware filesystem in my case. I can
imagine that the setup, at some point, may have heartbeat implementet
between so if one domU on fx. domO-1 gets inrespontant the domU gets
started on dom0-2. But at no point will more than one of the same domU
will be running.
as i see it, it's important to use cluster-aware tools, but not necessarily a
filesystem. if you can do live migration, any heartbeat daemon should be
able to trigger the migration.
Which volume manager is perferable to the other ? CLVM implies locking
mekanisme ? Can EVMS do the same ?
there are three options for a volume manager:
plain LVM: works ok on a cluster, but you have to bring it down to do any
modification to the volume group.
CLVM: the same as LVM, but uses the GFS lock manager to allow online
administration. the on-disk layout, device-mapper and everything else is
exactly the same as plain LVM, no extra overhead, nothing. doesn't depend on
a running GFS, just the lock manager and fencing.
EVMS: more generic than LVM, the administration utilities handle the whole
stack: physical devices, partitions, RAID, volume groups, logical volumes,
even filesystems. it's plugin architecture lets it manage md (for RAID), dm
(device mapper, used by LVM), and filesystems. can use LVM2 disk layout, and
coexist with LVM2. uses Linux-HA for heartbeat, fencing and locking,
becoming fully cluster-aware.
personally, i like more the LVM approach to do just one thing (join devices
and split them into logical volumes) and do it well, but the theory and
design of EVMS seems better and cleaner.
note that to turn plain LVM into CLVM, you have to install the GFS packages
and join the xen app servers to a cluster; there's no need to create a GFS
filesystem; just create the LVs
If I want to use DRBD can I start out with only 1 storage server or do I
need 2 storage servers ?
i don't have experience on this, but i guess you could add the mirror after
it's already working.
since DRBD also uses Linux-HA for the heartbeat, i guess it would be nicer to
use it too to make EVMS cluster-aware, even if the LVs are LVM2-compatible.
------------------------------------------------------------------------
_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users
_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users
|
|
|
Home