From: Kelly Sauke <ksauke@fastenal.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: AW: AW: [linux-lvm] SAN setup with host mirrored disks
Date: Mon, 17 Jul 2006 09:33:32 -0500 [thread overview]
Message-ID: <44BB9FBC.4080700@fastenal.com> (raw)
In-Reply-To: <7CA7BBF7F95AA245ACAB8E28A6285EB905191DB3@s01edv50.warema.de>
Fiederling, Daniel wrote:
> Currently I have only one path to each disk but further on I'd like to test a setup with multiple paths. But am I right that I have to use md on top of multipathd for getting the two disks mirrored?
>
Yes, multipathd only handles the multiple paths on a per disk basis. If
you need them mirrored you have to use something on top of the multipath
layer. Using md is one option that should work just fine.
> I tested different qla2xxx drivers (SuSE shipped, origanal download packages from qlogic, packages from hp) and the non suse offered much more module parameters - one of them was about en-/disabling failover. I would guess that the qla2xxx driver or the card firmware can handle multiple paths. But I'm not sure about that...
>
>
>
I've yet to meet an HBA that doesn't work with multiple paths. I would
check EMC's support matrix for your particular card. I know that we
have to run specific EMC firmware on our HBAs to be fully supported. I
think by running the non EMC firmware you lose some of the functionality
and may run into some stability issues. I can't comment on that further
since we've never done any testing with non-EMC firmware.
> -----Urspr�ngliche Nachricht-----
> Von: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] Im Auftrag von Kelly Sauke
> Gesendet: Montag, 17. Juli 2006 15:36
> An: LVM general discussion and development
> Betreff: Re: AW: [linux-lvm] SAN setup with host mirrored disks
>
>
>> Why do I have to expect io errors when using md? What is special about the Clariion setup? I would expect that the san disks are only "normal" scsi disks for linux...
>>
>>
> The difference comes in how the multiple paths to the same disk are
> handled under linux. If you only have one path to each disk, then this
> doesn't apply to you. I guess I forgot to clarify if you had more than
> one path. Anyway, if you have multiple paths mpio knows which is the
> Active path and which is the Passive path. Sending IO down a passive
> path will result in IO errors.
>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
next prev parent reply other threads:[~2006-07-17 14:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-12 22:04 [linux-lvm] SAN setup with host mirrored disks Fiederling, Daniel
2006-07-13 17:15 ` Luca Berra
2006-07-13 17:24 ` Michael Loftis
2006-07-13 18:03 ` Kelly Sauke
2006-07-17 6:11 ` AW: " Fiederling, Daniel
2006-07-17 13:36 ` Kelly Sauke
2006-07-17 13:54 ` AW: " Fiederling, Daniel
2006-07-17 14:33 ` Kelly Sauke [this message]
2006-07-17 17:34 ` Michael Loftis
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