Andreas Micklei wrote:
Am Mittwoch, 9. Mai 2007 schrieb Feizhou:
HW vs SW RAID: Kind of a religious question. HW has some advantages when
using RAID-5 or RAID-6 (less CPU load). When using RAID-0 or RAID-1 there
should not be any difference performance wise. HW RAID gives you some
advantages in terms of handling, i.e. hotplugging of discs, nice
administration console, RAID-10 during install ;-), etc. It's up to you
to decide whether it is worth the money. Plus you need to find a
controller that is well supported in Linux.
Hardware raid that comes with bbu write caches normally have a speed
boost in addition to the extra data safety too.
Also on RAID-0 and RAID-1? I have only used HW RAID without bbu, so I have no
experience with that. However you can tweak your filesystem and disks to do
write caching too, especially if you have plenty of RAM. Of course this means
living dangerously, so when you need performance and data safety HW RAID with
bbu is the only option of course.
Why did you think I specifically said hardware raid that comes with bbu
memory caches? RAM will always be faster than disk so if the hardware
raid stores stuff first in a bbu memory cache, it will always beat
software raid even on raid0,raid1.
Hardware raid without a bbu memory cache will always be slower on raid5
even if the raid processor is beefy enough.
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