in my tests with a mysql and similar database scenarios where write / read are near 50% / 50% (many updates/inserts and many selects) the best raid is 1 where scenario is 10%write / 90% read raid 10far is better (if not degraded or out of sync) just two scenarios to help 'what's better' question 2012/5/25 Bill Davidsen <davidsen@xxxxxxx>: > William Thompson wrote: >> >> On Wed, May 23, 2012 at 12:36:12AM +0200, David Brown wrote: >>> >>> On 22/05/12 21:33, William Thompson wrote: >>>> >>>> I understand that raid 10 f2 is slower on writes due to the location of >>>> the >>>> 2nd copy. My question is, if lots of writes are performed, could this >>>> layout wearout the drives quicker than raid 1? >>> >>> >>> No, wear is not going to be significantly different. >>> >>> You didn't say whether you are talking about hard disks (where >> >> >> Sorry about that (Chief). Yes, I was refering to hard drives. >> >>> location makes a difference, but "wear" on the drive motor is >>> insignificant to the disk's expected lifetime), or flash disks >> >> >> I was thinking about how much more head movement there would be to write >> the >> 2nd copy of the data. >> > There _is_ no extra head motion. The location of consecutive blocks is > different on each drive, but as I read the mapping function the distance > between blocks on the same drive will be about the same, so amount of head > motion (both number and distance) is the same on each drive, but the > location of that motion is not the same. > > One drive may be seeking at the outer edge of the platter while another > seeks near the spindle, but there's the same amount of seeking on each. > > > -- > Bill Davidsen <davidsen@xxxxxxx> > "We have more to fear from the bungling of the incompetent than from > the machinations of the wicked." - from Slashdot > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
