[CentOS] Recommendations for a “real RAID" 1 card on Centos box

Karanbir Singh mail-lists at karan.org
Mon Mar 10 01:03:24 UTC 2008


Therese Trudeau wrote:
> I'm just really looking for a RAID card that will do RAID 1, with four drive capacity, i.e.,
> a master drive with the OS and applications installed and mirrored, and a slave drive for data and
> photos, graphic design, video, etc also mirrored.  What would battery built into a RAID card 
> do for me? 

the whole point of a BBU is that you can turn on write back caching -
and get a fair win in write performance on regular tasks.

Also, make sure whatever raid hardware you decide to invest in supports
multiple raid sets ( thats what you seem to want - and not all raid
cards do that ) - both 3ware and Areca do support this.

Are you considering using this as a backup system and not doing any off
machine backups ? if so, consider the possibility of actually loosing
the raid card itself : Ideally you want the raid metadata sitting on the
disks rather than the raid card, so you can replace the card and be back
in action. Again, not all cards support this out of the box.

>>>> For me, in SATA RAID cards it's 3ware or nothing. Been using them for
>>>> more than 8 years now.
>> I used to think the same for a long time, till I started using Areca
>> raid cards. Now, I rate 3ware well behind Areca on performance,
>> reliability and ease of use. If you are doing raid-5 or raid-6 the
>> performance difference is quite noticeable ( I've just recently switched
>> my desktop from a 3ware 9650 to Areca 1220, and got a near 8%
>> improvement in write performance, and 12% on read - raid5 5 spindles ).
> 
> So you reccomend Areca, good thanks I'll check them out too.  How are they for RAID 1?

To be honest, its been a very long time since I used a raid-1 setup, and
I am not sure if I'd bother with it now. If you have 4 drives, might as
well raid-5 them. You still get the ability to loose 1 drive at a time,
and have a hot-spare : while ending up with the same storage capacity.

btw, if you have 4 drives, make sure they are as similar in
specifications as possible - however, try and get different batch
numbers / production runs. Drives that were made in the same batch, have
been stored and stock under the exact same conditions, shipped out
together, used and put into production together - have a very very high
probability of also failing together :D


-- 
Karanbir Singh : http://www.karan.org/ : 2522219 at icq



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