On Thu, 2006-03-23 at 15:37 +0100, Vanja Hrustic wrote:
> 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
Your hdparm numbers are slightly better than mine for the same drive.
For me: copying a 3.2GB file achieved 18.4MB/s
I guess hdparm is not a real-world indicator.
What does top tell you? Is something hogging the CPU.
Bob...
