switching from harware to kernel raid5

switching from harware to kernel raid5

[Louis-David Mitterrand]

Hello,

On one of our servers I upgraded the 3x4.2G disks to 3x18G and removed
the Mylex Acceleraid 160 in favor of pure kernel (2.4.18) root raid5
(reiserfs) with a small raid1 (ext2) boot partition.

The reasons I did this:

- latest kernel's stability,
- raid code time tested,
- simpler hardware configuration,
- transferability of the disks to a non Mylex-equiped box,
- better performance?

Is there any downside going from hardware to kernel raid5? It seems to
work very well. 

I even had to switch off the machine during testing because a loose PCI
card hung it: upong reboot the raid5 partition resynced itself fine. Was
I just lucky?

Thanks in advance for your insight, cheers,

-- 
    PHEDRE: Il suffit que ma main l'ait une fois touchée,
            Je l'ai rendue horrible à ses yeux inhumains ;
                                          (Phèdre, J-B Racine, acte 3, scène 1)
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Re: switching from harware to kernel raid5

[Jakob Østergaard]

On Mon, Apr 29, 2002 at 09:22:15AM +0200, Louis-David Mitterrand wrote:
> 
> Hello,
> 
> On one of our servers I upgraded the 3x4.2G disks to 3x18G and removed
> the Mylex Acceleraid 160 in favor of pure kernel (2.4.18) root raid5
> (reiserfs) with a small raid1 (ext2) boot partition.
> 
> The reasons I did this:
> 
> - latest kernel's stability,
> - raid code time tested,
> - simpler hardware configuration,
> - transferability of the disks to a non Mylex-equiped box,
> - better performance?
> 
> Is there any downside going from hardware to kernel raid5? It seems to
> work very well. 

The only downside that I can think of, is that noone has written drivers for
the typical hot-plug backplanes yet.  Therefore, you will not have a pretty LED
blinking to tell you which disk to replace.

For many people this is not really much of a problem.  But at some sites it is
- you cannot let the "server monkey" replace disks if there is no clear
  idiot-proof indication of which disk to replace.  At sites where the
competent administrator may be in a whole other building, this can be a
problem.

Actually, I'd love to see the pretty LEDs flashing when a disk dies too. It is
not a necessity for me, but it would be a convenience.

(mostly because I want the LEDs to do Night-Rider style flashing when the array
 is running normally  - weehee ! ;)

> 
> I even had to switch off the machine during testing because a loose PCI
> card hung it: upong reboot the raid5 partition resynced itself fine. Was
> I just lucky?

I suppose you were lucky you didn't toast your hardware.  :)

-- 
................................................................
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:.........................: putrid forms of man                :
:   Jakob Østergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............:
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