On 1/27/11 4:11 PM, "Alan Hodgson" <ahodg...@simkin.ca<mailto:ahodg...@simkin.ca>> wrote:
On January 27, 2011, Robert Schnabel <schnab...@missouri.edu<mailto:schnab...@missouri.edu>> wrote: > So my questions are 1) am I'm crazy for doing this, 2) would you change > anything and 3) is it acceptable to put the xlog & wal (and perhaps tmp > filespace) on a different controller than everything else? Please keep > in mind I'm a geneticist who happens to know a little bit about > bioinformatics and not the reverse. :-) > Putting the WAL on a second controller does help, if you're write-heavy. I tried separating indexes and data once on one server and didn't really notice that it helped much. Managing the space was problematic. I would suggest putting those together on a single RAID-10 of all the 300GB drives (minus a spare). It will probably outperform separate arrays most of the time, and be much easier to manage. If you go this route, I suggest two equally sized RAID 10's on different controllers fir index + data, with software raid-0 on top of that. RAID 10 will max out a controller after 6 to 10 drives, usually. Using the OS RAID 0 to aggregate the throughput of two controllers works great. WAL only has to be a little bit faster than your network in most cases. I've never seen it be a bottleneck on large bulk loads if it is on its own controller with 120MB/sec write throughput. I suppose a bulk load from COPY might stress it a bit more, but CPU ends up the bottleneck in postgres once you have I/O hardware this capable. -- A hybrid Escalade is missing the point much in the same way that having a diet soda with your extra large pepperoni pizza is missing the point.
