Multipath iSCSI

[John]

----- P??ter Szab??'s Original Message -----
> Dear *,
> 
> I have started to build a HA system. It runs a postgresql cluster with
> two nodes (master and hot stand-by, FreeBSD 9.0, postgresl 9.1). The
> storage for the database is provided by 2 separate systems (FreeBSD
> 9.0, iSCSI target, over ZFS). For the maximum redundancy I would like
> to use multipathing on the DB nodes. For me the best would be if the 2
> DB nodes and the 2 storage nodes are all FreeBSD.
> 
> Now I have 4 installed FreeBSD 9.0, iSCSI targets are in place, and
> the database nodes uses the exported targets as a storage. What is
> left is the multipath part.
> 
> I have search a lot in this topic, but now I am really confused. I
> found some mails from this mailing list, the problem was the same, and
> there was no solution, but the mails are quite old (FreeBSD 7.3). I
> checked gmultipath, but it seems it is not the solution.
> 
> Does FreeBSD support iSCSI multipath currently, or should I change the
> OS under the database nodes from FreeBSD to some linux distribution. I
> found a lot of working configuration for linux and iSCSI multipathing.

Hi,

This may not be the answer you're looking for.

iscontrol TargetName=disk1_net1 TargetAddress=...
iscontrol TargetName=disk1_ne12 TargetAddress=...

You now have access to the same lun via two different paths.

Now create a gmultipath entity (if the above came in as da1 & 2):

gmultipath label -Av MULTIPATH /dev/da1 /dev/da2

The above should create:

/dev/multipath/MULTIPATH

which should provide the characteristics you're looking for. The -A
option creates the device in active/active mode.

Good Luck,
John
   
> Cheers,
> 
> Matyee