Hi, I configured a similar architecture some months ago and this is the best choice after some pgbench and Bonnie++ tests. Server: DELL R720d CPU: dual Xeon 8-core RAM: 32GB ECC Controller PERC H710 Disks: 2xSSD (MLC) Raid1 for Operating System (CentOS 6.4) 4xSSD (SLC) Raid10 for WAL archive and a dedicated "fast tablespace", where we have most UPDATE actions (+ Hot spare). 10xHDD 15kRPM Raid5 for "default tablespace" (optimized for space, instead of Raid10) (+ Hot spare).
Our application have above 200 UPDATE /sec. (on the "fast tablespace") and above 15GB per die of records (on the "default tablespace"). After the testing phase I had the following conclusion: 4xSSD (SLC) RAID 10 vs. 10xHDD RAID 5 have comparable I/O performance in the sequential Read and Write, but much more performance on the Random scan (obviously!!), BUT as far I know the postgresql I/O processes are not heavily involved in a random I/O, so at same price I will prefer to buy 10xHDD instead of 4xSSD (SLC) using above 10x of available space at the same price!! 10xHDD RAID 10 vs. 10xHDD RAID 5 : with Bonnie++ I noticed a very small difference in I/O performance so I decided to use RAID 5 + a dedicated Hot Spare instead of a RAID10. If I could go back, I would have spent the money of the SLC in other HDDs. regards. 2014-02-17 16:03 GMT+01:00 Niels Kristian Schjødt < nielskrist...@autouncle.com>: > Hi, > > I’m kind of a noob when it comes to setting up RAID controllers and > tweaking them so I need some advice here. > > I’m just about to setup my newly rented DELL R720 12. gen server. It’s > running a single Intel Xeon E5-2620 v.2 processor and 64GB ECC ram. I have > installed 8 300GB SSDs in it. It has an PERC H710 raid controller (Based on > the LSI SAS 2208 dual core ROC). > > Now my database should be optimized for writing. UPDATEs are by far my > biggest bottleneck. > > Firstly: Should I just put all 8 drives in one single RAID 10 array, or > would it be better to have the 6 of them in one RAID 10 array, and then the > remaining two in a separate RAID 1 array e.g. for having WAL log dir on > it’s own drives? > > Secondly: Now what settings should I pay attention to when setting this > up, if I wan’t it to have optimal write performance (cache behavior, write > back etc.)? > > THANKS! > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
