I have installed CentOS 4.2, recently, on new computer.
Everything seemed to work fine.
However, we've found out that disk transfers are incredibly slow, and I
just can't figure out what to do in order to fix it.
Computer is now running CentOS 4.3 (updated it 1 hour ago), and same
thing is still present. I hoped kernel upgrade might fix it, but it
didn't.
Computer has 2 SATA disks, 200GB (Maxtor 6Y200M0) and 80GB (Maxtor
6L080M0).
There are no errors or any other indications of problems in logs/dmesg.
Copying 500MB file takes around 210 seconds. Around 2.3MB/sec.
Doesn't matter if I am copying from one hard disk to another, or onto
the same hard disk.
When copying, vmstat shows:
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 160 525928 1060 278044 0 0 1609 1112 1387 1146 9 4 39 47
0 0 160 525928 1060 278044 0 0 0 0 1084 745 0 0 100 0
0 0 160 525844 1060 278044 0 0 0 0 1067 795 2 0 98 0
0 0 160 525844 1060 278044 0 0 0 0 1084 745 1 0 99 0
0 0 160 525844 1072 278044 0 0 0 156 1073 757 0 0 100 0
0 1 160 525564 1148 278228 0 0 240 0 1129 1136 2 1 77 20
0 1 160 522708 1176 281256 0 0 1600 0 1283 1155 0 2 0 98
0 1 160 519380 1184 284568 0 0 1672 0 1327 1231 0 2 0 98
3 1 160 516404 1196 287368 0 0 1412 0 1264 1126 1 1 0 98
0 1 160 513524 1196 290424 0 0 1536 0 1353 1926 11 2 0 87
0 3 160 510132 1208 293544 0 0 1544 7348 1407 2163 24 6 0 71
0 1 160 513780 1216 289972 0 0 1412 140 1360 1536 9 3 0 88
2 0 160 515316 1220 288464 0 0 1104 0 1341 2067 47 4 0 49
0 1 160 518996 1216 284608 0 0 1712 0 1333 1676 34 7 0 59
0 1 160 516820 1224 286832 0 0 2052 0 1318 2025 25 4 0 71
1 2 160 512388 1228 291024 0 0 2952 8736 1433 1431 6 4 0 90
2 1 160 504772 1244 295304 0 0 3076 76 1382 1453 15 5 0 80
0 1 160 502340 1252 301096 0 0 3332 0 1358 1624 7 5 0 88
0 1 160 495236 1260 308216 0 0 3588 0 1323 1631 2 3 0 95
1 1 160 487620 1268 315640 0 0 3716 0 1355 1175 7 2 0 91
0 2 160 480708 1276 322120 0 0 3204 16732 1423 1354 2 5 0 93
You can see text version here (in case this got wrapped):
http://www.vanja.com/vmstat.txt
I've tried vmstat on my machine, with IDE disks, and I've noticed that I
ave much less 'cs' (context switches), although it might be because I'm
not having as many processes in the background (problematic computer
is running KDE :).
On my computer, number of blocks in (bi) gets into tens of thousands,
while problematic computer has 1500-3000 bs/second.
Does anyone know what I might do in order to find what the problem
might be?
I couldn't find any SATA specific tools, which might help with
troubleshooting. hdparm -tT tests show:
/dev/sda:
Timing cached reads: 2408 MB in 2.00 seconds = 1202.98 MB/sec
Timing buffered disk reads: 150 MB in 3.02 seconds = 49.61 MB/sec
/dev/sdb:
Timing cached reads: 2628 MB in 2.00 seconds = 1313.54 MB/sec
Timing buffered disk reads: 166 MB in 3.02 seconds = 54.88 MB/sec
All filesystems are ext3.
This "problematic" computer has nforce3 motherboard, I have nforce2.
Same CentOS, but no SATA on my computer.
This really affects complete performance of computer, and any help or
ideas are welcome.
Btw, no problems with transfer under Windows :(
Thanks.
Vanja
