[CentOS] HA Storage Cookbook?

Rudi Ahlers rudiahlers at gmail.com
Sat Nov 8 09:07:57 UTC 2008


On Fri, Nov 7, 2008 at 9:03 PM, Les Mikesell <lesmikesell at gmail.com> wrote:
> Gordon McLellan wrote:
>>
>> Les,
>>
>> That's pretty much my problem.  I was hoping to kill two birds with
>> one stone here.  First order of business is to replace the single
>> drive with a raid array.  Second order was to replace a single iscsi
>> server with duo of machines.  If one machine had some sort of
>> non-recoverable problem, the other could pick-up the torch and carry
>> on, even if that means I need to "flip a switch" to make it happen.
>>
>
> My solution for semi-critical stuff (i.e. a few minutes of downtime won't
> cost the 6 figures it would take to prevent it) has been to use RAID1 in a
> chassis with hot-swap carriers and keep a spare chassis handy.  That way the
> common case of a disk failure doesn't even cause a slowdown and you can
> rebuild at an off-peak time without shutting down and in the much less
> likely case of a motherboard failure you yank the drives, put them in the
> other box and reboot.  But, that means you are probably limited to 6 disks
> total with half used as mirrors and you still need backups for software or
> site disasters.
>
> The next step up from this would be DRBD to keep hot copies on the spare
> machine but I've always gotten away with one spare chassis for several
> active servers (and sometime using it for testing other things too...).
>
> You do need to know about the NIC hardware address in
> /etc/sysconfig/ifcfg-eth? when swapping disks around, though.
>
> --
>  Les Mikesell
>   lesmikesell at gmail.com
> _______________________________________________


I've been contemplating a setup similar to what you're referring to.

Basically, take two PC's, (say a Dell PE 860 - I got some of these),
and then network-RAID the two PC's, and setup them up with HA to offer
one single IP to the network.

Thus, if either one of them fails, you still have the other one left.

If space (i.e. rackspace) is a problem, then 2x1U's won't cost that
much, and they can take 2 HDD's each, so you could seup RAID 1
(mirror) on the 2 HDD's as well.

If you can afford 2U space, then you can setup a 2950 with 6 drives
each, which has more capacity, and the 2 servers clustered will give
redundancy.

Has anyone done something like this? What was your experience with
this? I know SuperMicro has a chassis that can take 2x small factor
motherboards, which means you can setup something like this on the
same chassis.


-- 

Kind Regards
Rudi Ahlers


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