Messages in this thread | | | From | Denis Vlasenko <> | Subject | Re: Horrible drive performance under concurrent i/o jobs (dlh problem?) | Date | Mon, 23 Dec 2002 16:13:37 -0200 |
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On 18 December 2002 17:06, Torben Frey wrote: > Hi list readers (and hopefully writers), > > after getting crazy with our main server in the company for over a > week now, this list is possibly my last help - I am no kernel > programmer but suscpect it to be a kernel problem. Reading through > the list did not help me (although I already thought so, see below). > > We are running a 3ware Escalade 7850 Raid controller with 7 IBM > Deskstar GXP 180 disks in Raid 5 mode, so it builds a 1.11TB disk. > There's one partition on it, /dev/sda1, formatted with Reiserfs > format 3.6. The Board is an MSI 6501 (K7D Master) with 1GB RAM but > only one processor. > > We were running the Raid smoothly while there was not much I/O - but > when we tried to produce large amounts of data last week, read and > write performance went down to inacceptable low rates. The load of > the machine went high up to 8,9,10... and every disk access stopped > processes from responding for a few seconds (nedit, ls). An "rm" of > many small files made the machine not react to "reboot" anymore, I > had to reset it.
Can you provide solid numbers (say Mb/s) of single dd's of varying size? Of concurrent dd's? etc...
> When I am working all alone on the disk creating a 1 GB file by > time dd if=/dev/zero of=testfile bs=1G count=1 > results in real times from 14 seconds when I am very lucky up to 4 > minutes usually. > Watching vmstat 1 shows me that "bo" drops quickly down from rates in > the 10 or 20 thousands to low rates of about 2 or 3 thousands when > the runs take so long.
Yes, and provide us with vmstat, top, cat /proc/meminfo output and the like! -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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