Saso Kiselkov wrote:
On 7/23/14, 12:57 PM, Miles Fidelman via illumos-discuss wrote:
Hi Folks,
Is there anything like DRBD or HAST for illumos? Seems like ZFS + DRBD
would be really sweet for high availability clusters - but so far, none
of the pieces are together in one place.
Trying to get to a small cluster w/ Xen+ZFS+HA
ZFS: illumos, FreeBSD, not really stable anywhere else
Replication: DRBD for Linux, HAST for BSD*, ??? for illumos
Xen: Linux, NetBSD
Sigh...
AFAIK there's no native remote block-level synchronous replication
solution for Illumos.
For async replication, incremental snapshots are the way to go. Just
transfer an incremental snapshot every 30-60s. They're relatively
inexpensive and robust, so pool corruption doesn't immediately get
propagated to the replication pair.
For sync replication I personally use SAS fabrics and mirrored pools
(conceptually, this is essentially what sync replication does, only over
a special protocol). Passive SAS cabling can run 3m (so rack-to-rack is
possible) and 20m with active cabling (room-to-room even). If longer
links are needed I'd opt for iSCSI. At Nexenta we've got some early
stuff in ZFS that allows us to prioritize reads & writes to mirror
sides, but it's still pretty new and not battle proven.
I know these are conceptually not exactly the same as DRBD or HAST, but
functionally it's identical.
Thanks for the model. It's kind of overkill for what we're doing - tiny
(4-node) cluster, mostly for development, but we run mail and a list
manager in a HA-configuration.
The basic stack, right now is:
VM (Debian Dom1)
DRBD
LVM
software raid
Xen (Debian Linux Dom0)
Pretty stable, except... if you're following the Linux world, and the
stuff w/ systemd (moving lots of core functions into a monolithic blob)
- instead of upgrading Linux, I've been seriously looking at migrating
to either a BSD or Solaris based stack. Complicated by having a couple
of older machines in our cluster that don't have hardware virtualization
extensions.
Kind of what I'd LIKE to do is:
VM (illumos if I can get all the mail, list, antivirus, etc. to run,
otherwise Linux)
<something like DRBD or HAST>
ZFS (exported ZVOL)
Xen (illumos-based Dom0)
Can't seem to find a full set of comparable software in either the BSD*
or illumos worlds. Sigh...
Thanks,
Miles
--
In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra
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