Our network guy did a bunch of benchmarking on the drives and found that SCSI-RAID5 was a bit faster than SATA-RAID0+1.
The SATA was significantly cheaper (the 3Ware card was the same price as the Megaraid card, however). You might be able to tie a 10K SCSI rig if you went with the Western Digital Raptor drives.
We ended up putting the SATA drives in production - some bug in the SCSI driver kept crashing MySQL on index-creation, etc.
High Performance MySQL mentions that SCSI 15K drives are worth the extra money.
Fast hard drives are important, but so is lots of RAM (which is where the Opteron shines). In fact, all the benchmarks I've seen show that the Opteron/Athlon architecture beats Intel processors by a 30-odd percent margin if memory serves (note that for some reason, most benchmarks I've seen were on 3.23, which is outdated and not overly usefull).
One of our websites serves up 2 million distinct pages per day; the original coders of the site did something dumb and open a new connection to the database for most of those pages (probably about 1.8 million). Even with that additonal load, our Opteron server has an average CPU load of about 10%.
David
Jan Kirchhoff wrote:
Egor Egorov wrote:
Money is not really an issue but of course we don't want to waste it for scsi-hardware if we can reach almost the same speed with hardware sata-raids.
'Almost' is a key word. Some SCSI disk are working at 15k RPM, which will give
you a HUGE MySQL performance growth compared to 10k disks.
AFAIR, there are no 15k RPM SATA disks yet.
But shouldn't a sata-based RAID10 with 8 discs do job as well? writes would be spread on 4 discs...
Has anybody experience with those external SCSI-to-SATA RAIDs?
A SCSI-solution would cost twice as much, but would it really speed things up compared to a massive use of parallel (raid0) sata-discs?
I know disc i/o is the bottleneck in our case, of course we want the fastest disc/raid-system we can possibly get for our money.
Is our thinking too simple or shouldn't it be possible to reach the speed of fast scsi-discs by simply taking 2-3 fast sata-discs in a hardware raid0?
Our goal is a raid10, so reading should be even faster.
Has anybody experiences with RAM-usage and cpu-architecture (please have a look at my earlier post)?Money is not really an issue but of course we don't want to waste it for We'd like to stay with x86 because all our hardware is intel/amd and all our servers are running debian-linux. Can we expect better performance or problems using kernel 2.6.x?
You can expect better performance on kernel 2.6.x of course, especially on
multiple requests.
thanks Jan
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