On Fri, 03 Aug 2012 15:37:36 +0200 David Brown <david.brown@xxxxxxxxxxxx> wrote: > That's not how I understand the disk layout - if I'm right, it is still > a monstrosity, but one that will offer protection on disk failure. > > As I read it, he has this (prior to adding the new disk): > > md0 = raid6(sda5, sdb5, sdc5, sdd5, sde5) > md1 = raid6(sda6, sdb6, sdc6, sdd6, sde6) > ... > md9 = raid6(sda14, sdb14, sdc14, sdd14, sde14) > > If that's the case, then it will be an administrative mess (as the OP is > now experiencing), but it will protect the data, and if the LVM is a > linear concatenation of these then performance normally will be okay. If you want the RAID5/6 write performance to be okay, you will want to increase stripe_cache_size to a good value [1] -- and that's per array, and the RAM consumption increases linearly with disk count - so on 10 five-member arrays you won't have anywhere near enough RAM to have a sufficient stripe_cache on all of them. In other words, one more aspect in which this multi-array configuration is highly suboptimal. :) [1] http://peterkieser.com/2009/11/29/raid-mdraid-stripe_cache_size-vs-write-transfer/ -- With respect, Roman ~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Stallman had a printer, with code he could not see. So he began to tinker, and set the software free."
Attachment:
signature.asc
Description: PGP signature
