[CentOS] Harware vs Kernel RAID (was Re: External SATA enclosures: SiI3124 and CentOS 5?)
rswwalker at gmail.com
Tue Jun 2 21:01:56 UTC 2009
On Tue, Jun 2, 2009 at 12:59 PM, Gordon Messmer <yinyang at eburg.com> wrote:
> On 06/01/2009 07:52 PM, Michael A. Peters wrote:
>> I've read a lot of different reports that suggest at this point in time,
>> kernel software raid is in most cases better than controller raid.
> There are certainly a lot of people who feel that way. It depends on
> what your priorities are. Hardware RAID has the advantage of offloading
> some calculations from the CPU, and has a write cache which can decrease
> memory use. However, both of those are relatively expensive, and
> there's no clear evidence that your money is better put into the RAID
> card than into faster CPU and more memory. Another important
> consideration is that hardware RAID will (must!) have a battery backup
> so that any scheduled writes can be completed later in the case of power
> loss. If you decide to use software RAID, I would strongly advise you
> to use a UPS, and to make sure your system monitors it and shuts down in
> the event of power loss.
I'd advise anybody who manages server equipment always UPS it. It's
not just power losses that can ruin your day, a power spike can take
out a power supply just as easily and a UPS conditions the power so
the output level is constant.
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