Re: Recommendations for configuring a 200 GB - Mailing list pgsql-performance

Thanks for your reply.  Besides your post regarding *nix vs. Windows I
got a few which didn't go to the group.  Words like "bold move" and
"disaster waiting to happen" tended to feature prominently in these
messages (regarding putting something this big on PostgreSQL under
Windows), and management is considering deploying one under Windows and
one under Linux, or possibly even both under Linux -- so please pass
along advice for either environment.

The four web servers are not all identical -- we have two "large" and
two "small".  They are split between sites, and even one of the small
ones is capable of keeping our apps running, although with significantly
impaired performance.  The initial PostgreSQL implementation will be on
one large and one small, unless we decide to do one each of Windows and
Linux; in that case we'd want identical hardware to better compare the
OS issues, so it would probably be the two small servers.

The small servers are IBM 8686-9RX servers with 4 xeon processors at 2
ghz, 6 gig of ram.  The internal drives are set as a 67 gig raid 5 array
with three drives.  We have an external storage arry attached.  This has
a 490 gig raid 5 array on it.  The drives are 15K drives.

http://www-307.ibm.com/pc/support/site.wss/quickPath.do?quickPathEntry=86869rx
for more info.

The large servers are also IBM, although I don't have a model number
handy.  I know the xeons are 3 ghz and the bus is faster; otherwise they
are similar.  I know the large servers can go to 64 GB RAM, and
management has said they are willing to add a lot more RAM if it will
get used.  (Our current, commercial database product can't use it under
Windows.)  There is also the possibility of adding additional CPUs.

Like I said, with the current hardware and Sybase 12.5.1, one small
machine can keep the applications limping along, although data
replication falls behind during the day and catches up at night, and we
get complaints from web users about slow response and some requests
timing out.  One large machine handles the load with little degradation,
and using any two machines keeps everyone happy.  We have four so that
we can have two each at two different sites, and so we can take one out
for maintenance and still tolerate a singe machine failure.

We're hoping PostgreSQL can match or beat Sybase performance, and
preliminary tests look good.  We should be able to get some load testing
going within a week, and we're shooting for slipping these machines into
the mix around the end of this month.  (We've gone to some lengths to
keep our code portable.)

-Kevin


>>> Richard Huxton <dev@archonet.com> 06/09/05 3:06 AM >>>
Kevin Grittner wrote:
>
> The manager of the DBA team is reluctant to change both the OS and the
> DBMS at the same time, so unless I can make a strong case for why it
is
> important to run postgresql under Linux, we will be running this on
> Windows.  Currently, there are two Java-based middle tier processes
> running on each central database server, one for the replication and
one
> for the web.  We expect to keep it that way, so the database needs to
> play well with these processes.

Well, there's a lot more experience running PG on various *nix systems
and a lot more help available. Also, I don't think performance on
Windows is as good as on Linux/*BSD yet.

Against switching OS is the fact that you presumably don't have the
skills in-house for it, and the hardware was chosen for Windows
compatibility/performance.

Speaking of which, what sort of hardware are we talking about?

--
   Richard Huxton
   Archonet Ltd