| Thanks both of you for your input.
Earlier I have been discussing my extremely high IO wait with you here on the mailing list, and have tried a lot of tweaks both on postgresql config, wal directly location and kernel tweaks, but unfortunately my problem persists, and I think I'm eventually down to just bad hardware (currently two 7200rpm disks in a software raid 1). So changing to 4 15000rpm SAS disks in a raid 10 is probably going to change a lot - don't you think? However, we are running a lot of background processing 300 connections to db sometimes. So my question is, should I also get something like pgpool2 setup at the same time? Is it, from your experience, likely to increase my throughput a lot more, if I had a connection pool of eg. 20 connections, instead of 300 concurrent ones directly? On Fri, Mar 1, 2013 at 3:43 AM, Niels Kristian Schjødt <nielskristian@xxxxxxxxxxxxx> wrote:
Hi, I'm going to setup a new server for my postgresql database, and I am considering one of these: http://www.hetzner.de/hosting/produkte_rootserver/poweredge-r720 with four SAS drives in a RAID 10 array. Has any of you any particular comments/pitfalls/etc. to mention on the setup? My application is very write heavy.
I can only tell you our experience with Dell from several years ago. We
bought two Dell servers similar (somewhat larger) than the model you're
looking at. We'll never buy from them again.
Advantages: They work. They haven't failed.
Disadvantages:
Performance
sucks. Dell costs far more than "white box" servers we buy from a
"white box" supplier (ASA Computers). ASA gives us roughly double the
performance for the same price. We can buy exactly what we want from
ASA.
Dell did a disk-drive "lock in." The RAID controller won't spin up a
non-Dell disk. They wanted roughly four times the price for their
disks compared to buying the exact same disks on Amazon. If a disk went
out today, it would probably cost even more because that model is
obsolete (luckily, we bought a couple spares). I think they abandoned
this policy because it caused so many complaints, but you should check
before you buy. This was an incredibly stupid RAID controller design.
Dell tech support doesn't know what they're talking about when it
comes to RAID controllers and serious server support. You're better off
with a white-box solution, where you can buy the exact parts
recommended in this group and get technical advice from people who know
what they're talking about. Dell basically doesn't understand Postgres.
They boast excellent on-site service, but for the price of their
computers and their service contract, you can buy two servers from a
white-box vendor. Our white-box servers have been just as reliable as
the Dell servers -- no failures.
I'm sure someone in Europe can recommend a good vendor for you.
Craig James
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