Re: [linux-lvm] SAN setup with host mirrored disks

[Kelly Sauke <ksauke@fastenal.com>]

Michael Loftis wrote:
>
>
> --On July 13, 2006 12:04:01 AM +0200 "Fiederling, Daniel" 
> <daniel.fiederling@warema.de> wrote:
>
>>
>> Hi,
>>
>> I'm relatively new to SAN setup with linux boxes, so maybe this is a 
>> very
>> easy question. Today I set up a linux box with two qlogic hbas, each one
>> is connected to a EMC Clarion. So I got two disks (/dev/sda and 
>> /dev/sdb)
>> from my storages that I have to mirror on the host system. There is on
>> mirror set up in the san environment!
>
> Uhhhmm...Clariion Can and does do RAID 0,1,5, as well as any 
> combination of the three.  Depending on the model of Clariion and your 
> specific setup (esp depending on if you're using powerpath or not) 
> you'll see one or two 'copies' of each LUN.
>
> In fact I'd highly recomment using the Clariion to do all of your real 
> RAID stuff, and if you can't use powerpath, then use md *just* for 
> failover. You do not need MD for actual RAID with a Clariion.  
> Navisphere will allow you to configure mirrors of sets of drives.
>
>
Do the Raiding on the Clariion.  Then use either PowerPath or mpio (on 
RHEL 4 U3 or newer) to do your failover.  If you use md for your 
failover layer you may get IO errors on the non-active paths.  You need 
something that is aware of the clariion setup and that would be 
PowerPath or the shipped mpio.


>
>
> -- 
> "Genius might be described as a supreme capacity for getting its 
> possessors
> into trouble of all kinds."
> -- Samuel Butler
>
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