[Users] iSCSI multipath with EqualLogic SAN

[Jonathan Horne]

Ive discussed this at length with dell's EQ support team, and on a regular system that's connected in to an equallogic san, all the iscsi ports would be on the same subnet.  The kicker is, dell really wants you to use their specialized driver/iscsiinitiator to access (known as their HIT kit...host integration tools), and the HIT kit handles establishing all the multiple sessions into the EQ SAN.

Unfortunately, equallogic  doesnt support RHEV (and thus ovirt), and ovirt does not seem to execute the commands the HIT driver would want to intitiate multiple connections.

Dell says that the use of bonding for iscsi just begs for tcp retransmits.  since bonding is the only method of failover I see for now, were using anyway against their recommendations (so far zero retransmits, but were not running our systems hard yet).

Cheers,
Jonathan

-----Original Message-----
From: users-bounces at ovirt.org [mailto:users-bounces at ovirt.org] On Behalf Of Sven Knohsalla
Sent: Thursday, February 21, 2013 8:55 AM
To: Baptiste AGASSE
Cc: users at ovirt.org
Subject: Re: [Users] iSCSI multipath with EqualLogic SAN

Hi Baptiste,

usually a SAN doesn't support bonding (see post of Nicolas) of its interfaces, so you have to use multipathing technology.

You have to separate all nics in different subnets so multipath can work.
Command multipath -ll with show the connected paths.

If you "merge" all paths in one subnet you will have the result/behavior you just posted.

So this is less oVirt related, more network specific.
We have a running iSCSI config with 4 networks and oVirt runs well.

Maybe the following link will help you here:
https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/pdf/DM_Multipath/Red_Hat_Enterprise_Linux-6-DM_Multipath-en-US.pdf

Cheers,
Sven.

-----Ursprüngliche Nachricht-----
Von: users-bounces at ovirt.org [mailto:users-bounces at ovirt.org] Im Auftrag von Nicolas Ecarnot
Gesendet: Donnerstag, 21. Februar 2013 15:48
An: users at ovirt.org
Betreff: Re: [Users] iSCSI multipath with EqualLogic SAN

Le 21/02/2013 11:30, Baptiste AGASSE a écrit :
> Hi all,
>
> I'm testing ovirt 3.1 on centos boxes. I setup ovirt management node
> and 4 vdsm hosts. vdsm hosts have 2 nics on the SAN subnet. When i
> create a iscsi storage domain, it use only one of the two nics on the
> SAN network (showed with iscsiadm -m session on vdsm nodes). Does
> ovirt support multiples nics on the same subnet for iscsi SAN
> connection ?

I don't know if this is the best setup, but this is exaclty what I did (iSCSI with an Equllogic SAN) : I bonded 4 interfaces of the iSCSI subnet, and it's working fine so far...

--
Nicolas Ecarnot
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