On 29-Apr-08, at 10:41 AM, Andrew Braithwaite wrote:
Hi,
Three things...
1. You need to let us know what the DB server will be doing. Many CPU
cores are only important of you have many CPU intensive MySQL
connections in parallel. Will you have a read-intensive or
write-intensive database load? Those 2950III you're considering can
take up to 8 disks. If you're doing very read-intensive operations,
you
may want to consider a RAID1 pair for your OS, apps and MySQL tmp
tables
and a RAID 5 array for the MySQL data (to get the most disk space for
your money without sacrificing redundancy). However; if you're
doing a
heavy work with lots of reads and writes at the same time then you
should consider RAID1+0 for your data. RAM will always help for both
MySQL caches and buffers and don't underestimate the great effect that
lots of RAM for your filesystem cache will have (talking about
unix/linux here, can't speak for windows).
Right now, averaging 13 queries / second.
47% SELECTS
14% INSERTS
22% UPDATES
7% CHANGE DB
I was thinking of doing a RAID 1/1 (four drives, all 15K SAS), with OS/
Apps on the first mirror, and MySQL data on the second.
I'm working at tuning my table definitions and queries and a few other
things in order to bring down the number of queries. Although I'm
using indexes liberally, it seems LEFT JOINs are killing the queries
that touch the 17 million row table. So I'm working on that. I want to
"fix" my own queries before moving to faster hardware, but in any
case, I would still like to get best iron for the task, long-term.
With 8 disks, would something like RAID1 for OS/Apps, then RAID1+0 for
MySQL data allow for substantially higher IO transactions? Row sizes
are very small, it's mainly a latency thing from what I can see.
2. All the hardware vendors have promotions running all the time which
they change every month. One month it will be cheaper disk, the next
month will be cut-price RAM etc... The end result will be about the
same...
I've just been hoping that Dell would drop the price on the 2950III.
It's been the same for about six months.
3. It's very easy to upgrade memory and processors as long as you
don't
mind 15 minutes or so of downtime for that server, linux will just see
the new h/w when it comes back up. With hardware like HP and Dell you
won't even need a screwdriver, it's all easy to use clips.
Good advice, thanks. From reading everyone's advice, I'm inclined to
save money on the CPU (just one quad-core Xeon 5430 at 2.66GHZ, 6MB L2
Cache) and spend more money on RAM (16GB instead of 8GB).
...Rene
