[CentOS] 4 X 500 gb drives - best software raid config for a backup server?

[Les Mikesell]

Ian Forde wrote:
> On Sat, 2009-02-21 at 18:09 -0600, Les Mikesell wrote:
>> Yes, but raid1 in software has none of those problems, since as far as 
>> the boot loader is concerned, you are booting from a single drive.  And 
>> there is a trade-off in complexity, since sw raid works the same on 
>> Linux across different hardware and you need to round up different 
>> vendors instructions and utilities for hardware raid - and have a backup 
>> controller around for recovery.
> 
> RAID in software, whether RAID1 or RAID5/6, always has manual steps
> involved in recovery.

Don't forget that 'recovery' sometimes means taking the still-working 
drives and moving them to a new chassis.

> If one is using standardized hardware, such as HP
> DL-x80 hardware or Dell x950 boxes, HW RAID obviates the need for a
> "recovery procedure".

As long as you have an exactly-matching chassis/motherboard/controller 
to move to.

> It's just easier.  You can still boot from a
> single drive, since that's what the bootloader sees.  There are no
> vendor instructions or utilities needed for recovery.  Nor is there a
> backup controller needed.

Everything breaks eventually.  If yours hasn't yet, good luck with that.

> The *only* time I'd use software RAID on
> Linux is if I didn't have a standard hardware base that supported
> hotswap and commandless recovery, which in any enterprise within which I
> were to be employed, I'd insist upon (and deploy)...

You can have hot spares in software raid if you can't be bothered to 
type 'mdadm --add ....' once every few years.

-- 
   Les Mikesell
    lesmikesell at gmail.com