Re: Help specifying new web server/database machine
От | William Yu |
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Тема | Re: Help specifying new web server/database machine |
Дата | |
Msg-id | d87v84$2ihi$1@news.hub.org обсуждение исходный текст |
Ответ на | Help specifying new web server/database machine (Rory Campbell-Lange <rory@campbell-lange.net>) |
Ответы |
Re: Help specifying new web server/database machine
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Список | pgsql-performance |
> We are considering two RAID1 system disks, and two RAID1 data disks. > We've avoided buying Xeons. The machine we are looking at looks like > this: > > Rackmount Chassis - 500W PSU / 4 x SATA Disk Drive Bays > S2882-D - Dual Opteron / AMD 8111 Chipset / 5 x PCI Slots > 2x - (Dual) AMD Opteron 246 Processors (2.0GHz) - 1MB L2 Cache/core (single core) For about $1500 more, you could go 2x270 (dual core 2ghz) and get a 4X SMP system. (My DC 2x265 system just arrived -- can't wait to start testing it!!!) > 2GB (2x 1024MB) DDR-400 (PC3200) ECC Registered SDRAM (single rank) This is a wierd configuration. For a 2x Opteron server to operate at max performance, it needs 4 DIMMs minimum. Opterons use a 128-bit memory interface and hence requires 2 DIMMs per CPU to run at full speed. With only 2 DIMMS, you either have both CPUs run @ 64-bit (this may not even be possible) or populate only 1 CPU bank -- the other CPU must then request all memory access through the other CPU which is a significant penalty. If you went 4x512MB, you'd limit your future update options by having less slots available to add more memory. I'd definitely out of the chute get 4x1GB, > 4 Port AMCC/3Ware 9500-4LP PCI SATA RAID Controller > 80GB SATA-150 7200RPM Hard Disk / 8MB Cache > 80GB SATA-150 7200RPM Hard Disk / 8MB Cache > 250GB SATA-150 7200RPM Hard Disk / 8MB Cache > 250GB SATA-150 7200RPM Hard Disk / 8MB Cache Now this is comes to the interesting part. We've had huge, gigantic threads (check archives for the $7K server threads) about SCSI versus SATA in the past. 7200 SATAs just aren't fast/smart enough to cut it for most production uses in regular configs. If you are set on SATA, you will have to consider the following options: (1) use 10K Raptors for TCQ goodness, (2) put a huge amount of memory onto the SATA RAID card -- 1GB minimum, (3) use a ton of SATA drives to make a RAID10 array -- 8 drives minimum. Or you could go SCSI. SCSI is cost prohibitive though at the larger disk sizes -- this is why I'm considering option #3 for my data processing server.
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