u235sentinel wrote:
The concern we have is our 4540 has a 2TB database which is working great. The server has 48 hard drives (250 gig drives) in RAID 10 across 6 disk controllers. A couple HBA controllers connected to a couple dozen disks may be slower (though dell assures us it will be faster than our Sun box).
A Dell system running a PERC with battery-backed write controller will be faster on database writes than your 4540. Those Sun boxes are terrible at OLTP style workloads in particular, the types of writes PostgreSQL does can't be cached by the hard drives in the Sun Thumper systems. It's possible to bottleneck at ~100 write transactions/second on them given a particularly incompatible application (I wrote one once, learned the hard way).
The flip side is that you can absolutely approach 2GB/s on reads on your Sun system, and I'd expect the Dell one will bottleneck somewhere in the 500MB-1GB/s range no matter how many controllers or drives you put into it. If your workload is so read heavy that you won't see any advantage from the write cache you're missing in your Sun box, it's absolutely possible for the Dell system to be a step backwards. A big Thumper box will chug away doing big reads against a 2TB database like it's no problem at all, as you already know.
While I generally dislike Dell, on the hard drive side of things the current PERC controllers are rebranded LSI Logic ones, and those seem to have the best performance while keeping reasonable reliability trade-off available right now. Dell just happens to have one of the best known formulas for building this sort of server right now.
-- Greg Smith 2ndQuadrant US Baltimore, MD PostgreSQL Training, Services and Support greg@xxxxxxxxxxxxxxx www.2ndQuadrant.us -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
