Date: Mon, 6 Feb 2012 13:37:38 +0200 From: Daniel Kalchev <daniel@digsys.bg> To: George Kontostanos <gkontos.mail@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: HAST considarations Message-ID: <FAE6B79D-6791-4B1F-8E0D-79BEB2765B3B@digsys.bg> In-Reply-To: <CA%2BdUSypg_3uNYMtU2tnvrvAPFw8MjM596tDZ=R_eqpE=GL1-=A@mail.gmail.com> References: <CA%2BdUSypg_3uNYMtU2tnvrvAPFw8MjM596tDZ=R_eqpE=GL1-=A@mail.gmail.com>
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My only issue with this setup is that on reboot, CARP becomes mater for =
a moment, then hears the other (real) master and switched to backup =
mode. This will however trigger the devd scripts. It can be fixed by =
more checks in the scripts, but really, CARP should not start as master.
Otherwise, I have beaten it a lot and it seems to work ok.
Daniel
On Feb 6, 2012, at 12:54 PM, George Kontostanos wrote:
> Greetings list,
>=20
> I have been experimenting with HAST on a raidz ZFS pool and I have
> stumbled upon some issues. So, any suggestions are highly appreciated
> :)
>=20
> My testing environment is consisted of a Linux KVM machine with an
> Intel Core2Duo and 4G RAM with 2 SATA drives striped (for performance)
> since I don't have the metal to experiment.
>=20
> When someone is considering to use a HA solution for storage then I am
> quite sure that their set up would include redundant switches and
> NICs. For best performance the HAST synchronization should be
> independent from the CARP interfaces, possibly consisting with more
> than 1 NIC with lag. At least that's what I think.
>=20
> The first problem appeared when trying to setup the resources. It
> seems that the resource name is tight up with the machines hostname.
> My hast.conf looks like this:
>=20
> resource disk1 {
> on hast1 {
> local /dev/da0
> remote hast2
> }
> on hast2 {
> local /dev/da0
> remote hast1
> }
> }
>=20
> resource disk2 {
> on hast1 {
> local /dev/da1
> remote hast2
> }
> on hast2 {
> local /dev/da1
> remote hast1
> }
> }
>=20
> However, the hostnames are storage1 and storage2 with storage being
> the shared CARP IP. Both hast1 & hast2 resolve in /etc/hosts and are
> connected to a different private vlan but when trying to create the
> first resource the system complained that only hast1 is an acceptable
> resource name.
>=20
> After changing both machines hostnames I was able to create the
> resources and a zpool mirror consisted upon /dev/hast/disk1 &
> /dev/hast/disk2
>=20
> Manual failover also worked by exporting the pool from the master,
> switching roles and then importing the pool on the slave. Yet, looking
> at the example scripts I realized that there is a lot of work to be
> done since automatic failover is based upon the CARP device and is
> limited to one resource. I replicated the resources at the script
> level in order to switch roles for all the devices. Still it looks
> very basic and crapy.
> Also, I added the NIC witch is being used for HAST replication to the
> /etc/devd.conf besides CARP
>=20
> I see this being at an early stage but I was wondering if anyone has
> to share some success (or not) stories. Also, does anyone else share
> my point regarding separating CARP and HAST replication? If yes I
> would be very interesting to know how this was done.
>=20
> Regards
>=20
> --=20
> George Kontostanos
> Aicom telecoms ltd
> http://www.aisecure.net
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