Linux RAID subsystem development
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* Multipath behavior
@ 2008-04-22 17:48 Billy Crook
  2008-05-08  5:12 ` Neil Brown
  0 siblings, 1 reply; 2+ messages in thread
From: Billy Crook @ 2008-04-22 17:48 UTC (permalink / raw)
  To: linux-raid

I am considering implementing multipath for iSCSI.  Documentation is
scant though, so I thought I'd ask my questions here.

Does mdadm multipath loadbalance IO, or just allow for failover, or both?
Is there any advantage to notifying mdadm pre-emptively if possible
before a path goes down?
I assume bringing a path online has to be done manually like adding a
disk.  Can spare paths be used?

The kernel involved is 2.6.18-53.1.14.el5.

Thank you for your time.
-Billy Crook

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: Multipath behavior
  2008-04-22 17:48 Multipath behavior Billy Crook
@ 2008-05-08  5:12 ` Neil Brown
  0 siblings, 0 replies; 2+ messages in thread
From: Neil Brown @ 2008-05-08  5:12 UTC (permalink / raw)
  To: Billy Crook; +Cc: linux-raid

On Tuesday April 22, bcrook@advancedclustering.com wrote:
> I am considering implementing multipath for iSCSI.  Documentation is
> scant though, so I thought I'd ask my questions here.
> 
> Does mdadm multipath loadbalance IO, or just allow for failover, or both?
> Is there any advantage to notifying mdadm pre-emptively if possible
> before a path goes down?
> I assume bringing a path online has to be done manually like adding a
> disk.  Can spare paths be used?
> 
> The kernel involved is 2.6.18-53.1.14.el5.
> 
> Thank you for your time.

I recommend against using md based multipath.  It is not being
seriously maintained.
dm (aka device mapper) based multipath is where the action is.

NeilBrown

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2008-04-22 17:48 Multipath behavior Billy Crook
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