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.