[Box Backup] Moving a server to RAID
boxbackup at fluffy.co.uk
Tue Mar 15 18:08:55 GMT 2005
On 3/15/05 2:38 AM, Jamie Neil wrote:
> dave bamford wrote:
>> 2. Would you recommend the mobo RAID or the FC3 sw RAID?
> Unless you are using a _true_ hardware RAID controller (like the 3ware
> ones) then you are better off using software RAID on Linux for a
> number of reasons:
> 1) Cheap hardware RAID controllers are essentially software RAID in
> disguise - no cache and most of the processing is done by the CPU.
> 2) Linux drivers for most RAID controllers are not very good, and some
> are binary only and so only work on specific kernel versions.
> 3) If the controller fails, you'll need to get another one exactly the
> same to boot your array (with embedded controllers this is even more
> of a problem). With software RAID you can move the array to another
> system and it will work fine.
> 4) Performance is roughly the same.
> The two main benefits of hardware RAID over software is caching and
> hot plug facilities, however these are only available on the higher
> end controllers.
I am using a 3Ware (8506-4LP) 'true hardware' controller on FC2, and
it's working great. Snappy, no problems with performance, and the driver
works fine. Also, the '3dmd' verifier daemon does its thing every week,
validating the array, and emailing me the results. The hot-swapping is
nice, too (although I haven't had to use it yet).
The disadvantages that Jamie mentions are definitely there, and I'm sure
that when I need more disk space, I will be using software RAID. For
example, I have a spare controller on hand for when my existing one
dies. That's $350 I'll never see again.
Hardware RAID has its place. If you need 99.999% uptime, then
hot-swapping is a key feature, and the hardware controllers are the answer.
If you're using the array as a Box Backup store, I think in most cases
software RAID is the perfect solution.
Per Reedtz Thomsen | Reedtz Consulting, LLC | F: 209 883 4119
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