Hi Robert, On Thu, May 3, 2012 at 1:28 AM, Robert Klemme <shortcut...@googlemail.com>wrote:
> Hi Jan, > > On Thu, May 3, 2012 at 4:10 AM, Jan Nielsen <jan.sture.niel...@gmail.com> > wrote: > > Below is the hardware, firmware, OS, and PG configuration pieces that I'm > > settling in on. As was noted, the local storage used for OS is actually > two > > disks with RAID 10. If anything appears like a mistake or something is > > missing, I'd appreciate the feedback. > > You should quickly patent this solution. As far as I know you need at > least four disks for RAID 10. :-) > http://en.wikipedia.org/wiki/RAID#Nested_.28hybrid.29_RAID > > Or did you mean RAID 1? > Ugh - yeah - sorry. RAID-1 for the 2-disk OS and WAL. > > I'm still working on the benchmarks scripts and I don't have > good/reliable > > numbers yet since our SAN is still very busy reconfiguring from the 2x4 > to > > 1x8. I'm hoping to get them running tomorrow when the SAN should complete > > its 60 hours of reconfiguration. > > Yeah, does not seem to make a lot of sense to test during this phase. > > > Thanks, again, for all the great feedback. > > You're welcome! > > > 300GB RAID10 2x15k drive for OS on local storage > Correction: RAID-1 on the 2x15k local storage device for OS > > */dev/sda1 RA* 4096 > > */dev/sda1 FS* ext4 > > */dev/sda1 MO* > > See above. > > > 600GB RAID 10 8x15k drive for $PGDATA on SAN > Clarification: RAID-10 on the 8x15k SAN device for $PGDATA > > *IO Scheduler sda* noop anticipatory deadline [cfq] > > */dev/sdb1 RA* 4096 > > */dev/sdb1 FS* xfs > > */dev/sdb1 MO* > > allocsize=256m,attr2,logbufs=8,logbsize=256k,noatime > > > > 300GB RAID 10 2x15k drive for $PGDATA/pg_xlog on SAN > Correction: RAID-1 on the 2x15k SAN device for $PGDATA/pg_log > > *IO Scheduler sdb* noop anticipatory deadline [cfq] > > */dev/sde1 RA* 4096 > > */dev/sde1 FS* xfs > > */dev/sde1 MO* > allocsize=256m,attr2,logbufs=8,logbsize=256k,noatime > > *IO Scheduler sde* noop anticipatory deadline [cfq] > > See above. > > With regard to the scheduler, I have frequently read that [deadline] > and [noop] perform better for PG loads. Fortunately this can be > easily changed. > > Maybe this also has some additional input: > http://www.fccps.cz/download/adv/frr/hdd/hdd.html > Thanks for the reference, Robert. > On Thu, May 3, 2012 at 8:54 AM, John Lister <john.lis...@kickstone.co.uk> > wrote: > > I was wondering if it would be better to put the xlog on the same disk as > > the OS? Apart from the occasional log writes I'd have thought most OS > data > > is loaded into cache at the beginning, so you effectively have an unused > > disk. This gives you another spindle (mirrored) for your data. > > > > Or have I missed something fundamental? > > Separating avoids interference between OS and WAL logging (i.e. a > script running berserk and filling OS filesystem). Also it's easier > to manage (e.g. in case of relocation to another volume etc.). And > you can have different mount options (i.e. might want to have atime > for OS volume). > > Kind regards > > robert > > > -- > remember.guy do |as, often| as.you_can - without end > http://blog.rubybestpractices.com/ >
