Re: RAID1 on Install of RHEL4

Bill Watson wrote :

> I have a Dell PERC and an original MegaRAID controller
under my control at
> various sites. I will do whatever I can to not repeat
those mistakes.

BERES Laszlo wrote :

> Matthias Saou wrote:
> 
> >   - IBM ServRAID controllers
> 
> Wooo, forget them! We had nightmares with these
"controllers": one of
> them simply deleted all of the RAID arrays, another
marked disks bad one
> after the other, etc.

Well, then I guess it's all a matter of personal experience.
If any
details of mine can be useful :

- I've used many PERC4 controllers, and the only annoying
thing I can
think of is the limitation of 2TB per volume. Luckily one
can quite
easily make multiple LVM PVs from less than 2TB volumes and
create one
huge LV on top of that. The PERC4 RAID arrays can easily be
monitored
with the "megarc" tool.

- The only ServRAID adapters I've used are now aging 3L and
4L
versions, but they've been real life savers quite a few
times : The
possibility to simply move drives configured as a RAID array
to another
server and choose to "import RAID configuration from
drives" at boot
time is really valuable for data recovery!

Matthias

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Matthias Saou wrote:
Well, then I guess it's all a matter of personal experience.
If any details
of mine can be useful :

- I've used many PERC4 controllers, and the only annoying
thing I can think
of is the limitation of 2TB per volume. Luckily one can
quite easily make
multiple LVM PVs from less than 2TB volumes and create one
huge LV on top of
that. The PERC4 RAID arrays can easily be monitored with the
"megarc" tool.

- The only ServRAID adapters I've used are now aging 3L and
4L versions, but
they've been real life savers quite a few times : The
possibility to simply
move drives configured as a RAID array to another server and
choose to
"import RAID configuration from drives" at boot
time is really valuable for
data recovery!

Matthias


Bill Responds:
On the MegaRAID controller, I have attempted to add a
replacement disk
numerous times. The rebuild tool appears to work for hours,
then the
controller reports a failure without any clues as to what
it's upset about.
A small drive was rebuilt fine, but a large drive always
fails. This was a 4
drive setup with 2 mirrored to 2 individually.

On the Dell PERC, bought from Dell with RedHat AS3.0 disks
(after AS4.0 came
out) IIRC the controller could only do RAID 0+1 if you
tricked it. The
software setup tool refused to do 0+1, but the BOIS would if
you forced it.
The Dell engineering group refused to help claiming that 0+1
was an
unsupported configuration. They only allowed 0 or 1 or 5. I
found this
severely limiting on a Server box. Also on a Dell server, do
not anticipate
that you can add CD's later without 6 order attempts across
4 months for the
specialty power cable and drive mounting brackets.

Bill Watson
billmagicdigits.com



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