Re: Hardware RAID, software RAID, 3ware 9550SX, level 1 vs. level 5
David Gaudine wrote:
I have to set up a system that is totally reliable w.r.t. data
integrity. That is, if a disk (or anything else) fails, it's OK if the
system is down for a few hours, but when it comes back up it has to be
exactly as it was, i.e. I can't restore from the previous day's backup.
The obvious solution is to use RAID level 1. Questions;
I have no other experience of raid apart that I run a server with
hardware raid and another one with software raid.
My personal experience (YMMV):
Hardware raid:
- not all hardware raids are well supported by linux.
- when I upgraded the hardware raid from kernel 2.4 to 2.6, the names of
my raid were changed; so I couldn't boot any more
- a few weeks before warranty expired, our hardware raid had a hardware
failure (had it happend a few weeks later, it would have been expensive
to repair: of course that particular hardware is out of production by now)
- when your hardware fails, you have to replace your special raid controller
Software raid (mdadm)
- software raid works well, never had problems
- installation and administration is straightforward
- if some other part of your hardware fails you can take the disks and
carry them to your next computer ;-) -- or just replace the motherboard,
etc.
- should work on any standard motherboard/hardware that supports the
number of disks your require (please correct, if I'm wrong)
Maybe that's biased by my personal distribution of good luck and bad
luck, so take it with a grain of salt.
Johannes
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