Re: RAID newbie...can I have several partitions on a RAID 1 array?

Previously Bob Willard <BobwBSGS@xxxxxxxxxxxxxxxxxxxxx> wrote:
Arno Wagner wrote:

Previously Ian R <sorry@xxxxxxxxxxxxxxxx> wrote:

Hi


I'm thinking of setting up a RAID 1 array with two 250GB Drives (7K250
SATAII )


This is my first venture into RAID so I have a few newbie questions...


Can I split the drive into several partitions or does it have to remain as a
single partition?


You can partition the RAID array. With most hardware-RAID set-ups you
cannot form the ARRAY from partitions, but juts whole disks.


If I can, will most software partition managers (PQ Partition Magic,
Acronis, Ghost) cope with RAID or do I need a special partition manager? Can
you recommend one?


Should work.


As far as my software is concerned I presume they ignore the RAID
aspect and just see it as a normal single drive?


Yes.


Just in case your were wondering... I am aware that RAID 1 is a
mirrored array. I'll be using the Sil 3114 RAID controller on my
ASUS A8N-SLI Premium Mobo.


One thing: For true redundancy, you need a spare controller. There is
software to reconstruct RAID data from the disks only, but (AFAIK) it
costs money and you need another disk. Hardware RAID 1 does not
protect you from controller failure and usually the disk layout is
specifically designed so that you cannot access the individual drives
without the controller. The only reason for this is to force you to
buy a new controller from the same company (i.e. corporate greed) as
you used to create the array. That it is possible to do this
differently is demonstrated by Linux software RAID 1: It places the
RAID descriptor at the end of the disk and you can access each disk
without RAID directly. Hardware controllers usually place the
descriptor at the beginning of the disk to prevent use of the
disk without controller.

Arno


I don't disagree with Arno at all: as he kinda said, for true
*hardware* redundancy, you need *at least* a spare controller.
But even total hardware redundancy does not supply any protection
against bad software (e.g., Windows) or against funble-fingers.

My conclusion: RAID is nice, but backup is essential.

Indeed. You are entirely correct of course. With current backup
you can do away with the spare controller. I am getting so used to
people here running without backup, that I start to overlook
the obvious. Thanks for reminding me!

As Bob says, RAID only protects from hardware problems, so it only
fills part of the things a backup does. Essentially RAID is a
''hassle reducer'': It decreases the probability that you need
to restore your backup.

Arno



.

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