On Sep 11, 2011, at 9:21 AM, Igor Chudov wrote: > > > On Sun, Sep 11, 2011 at 9:16 AM, Claudio Freire <klaussfre...@gmail.com> > wrote: > On Sun, Sep 11, 2011 at 3:59 PM, Igor Chudov <ichu...@gmail.com> wrote: > > Well, right now, my server has twelve 7,200 RPM 2TB hard drives in a RAID-6 > > configuration. > > They are managed by a 3WARE 9750 RAID CARD. > > > > I would say that I am not very concerned with linear relationship of read > > speed to disk speed. If that stuff is somewhat slow, it is OK with me. > > With Raid 6 you'll have abysmal performance on write operations. > In data warehousing, there's lots of writes to temporary files, for > sorting and stuff like that. > > You should either migrate to raid 10, or set up a separate array for > temporary files, perhaps raid 0. > > Thanks. I will rebuild the RAID array early next week and I will see if I > have a Raid 10 option with that card. > > Quantitatively, what would you say is the write speed difference between RAID > 10 and RAID 6? >
As someone who migrated a RAID 5 installation to RAID 10, I am getting far better read and write performance on heavy calculation queries. Writing on the RAID 5 really made things crawl. For lots of writing, I think RAID 10 is the best. It should also be noted that I changed my filesystem from ext3 to XFS - this is something you can look into as well. Ogden
