raid and lvm with 8 disks....suggestions?

[Ruben Laban]

On Wednesday 16 January 2008, Luca Ferrari wrote:
> I'm approaching a new server with 8x146GB SAS disks and an hardware
> controller. The server will store a lot of database data and will work also
> as a file server and I'm wondering what could be the better configuration
> for running it. My first thought was about 2x147 raid 1 for the system, and
> 5 raid 5 with 1 spare disk. The two disks in mirroring for the system
> itself and the raid5 for the data. Is this a good solution? Could it be
> better to make all the disks raid5? Moreover, I was thinking of activating
> lvm so that part of the raid1 array could be used as space for the data
> too, does it make sense? Any suggestion or link to a good documentation
> that can drive me to the choice?

Depending on the database usage of that server, RAID5 might not be the 
solution you want to go for. RAID5 has the downside of 'expensive' writes. If 
storage is less important than speed, I suggest you go for either RAID10 or 
RAID0+1 (mirrored stripe versus striped mirror). Using LVM over both the 
RAID1 and RAID5 as you suggested doesn't make much sense to me.
Using LVM in general has its pros and cons. Pro being that you can 
repartition 'safely' on-the-fly, con being that it might introduce a 
performance hit.

HTH.

Regards,
-- 
Ruben Laban
Systems and Network Administrator
r.laban at ism.nl
  
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