Are you sure the SATA disks are configured as SATA in the BIOS (enhanced/AHCI), and not emulated to PATA, then mapped using libata (which makes them /dev/sd* ?
Dan On 4/17/07, Amos Shapira <[EMAIL PROTECTED]> wrote:
Hi, We have a couple of boxes here which just receive tons of e-mail and do some file processing on it before moving it off for other servers to process. The boxes have two AMD Athlon X2 3200 64 bit processors on them, with 1Gb RAM and a SATA drive which identifies as Seagate ST3400620AS (product page at http://tinyurl.com/26c8wg). The disk controller identifies on lspci as: 00:0f.0 RAID bus controller: VIA Technologies, Inc. VIA VT6420 SATA RAID Controller (rev 80) The load average on these machines is way too high - one of them almost doesn't receive connections (it's a fall-back machine), both of them don't use the swap and still their load average is 13 and above (could peak at up to 90 for a few seconds/minutes), could be averaging above 20 most of the time on the busier machine. The strange thing I found about it (I look at the less busy box) is the output of vmstat: # vmstat 5 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 13 100 10448 232800 331344 0 0 208 1180 43 84 8 23 4 66 0 13 100 9116 232812 331332 0 0 246 465 384 357 0 1 0 99 0 13 100 9496 232816 331328 0 0 262 451 388 370 0 1 0 99 I'm looking at the "wa" column and I don't see why is it so high. "top" doesn't show any excessive amount of processes (not even insane amount of SMTP connections). Googling around about tuning SATA drives keeps coming back with answers to the tune of "SATA gets tuned automatically by the system already - there is nothing you can do about it as is possible/required with PATA/hdparm". Still, running "hdparm -tT /dev/sda" returns what seems to be reasonable cached reads but as far as I understand much slower buffered reads than I should expect: # hdparm -tT /dev/sda /dev/sda: Timing cached reads: 3220 MB in 2.00 seconds = 1608.69 MB/sec Timing buffered disk reads: 2 MB in 3.16 seconds = 648.12 kB/sec I can't take the system down to single-user for testing, though, so I'm not sure how meaningful are these numbers. The system run Fedora Core 5 and kernel 2.6.15-1.2054_FC5 and Sendmail 8.12 (at least until I get around to install Debian 4.0 and maybe convert the configuration to Postfix). Any hints on what can I do to improve the performance? Thanks, --Amos ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
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