Messages in this thread | | | Date | Wed, 23 Feb 2000 21:03:27 +0200 (EET) | From | Timo Jantunen <> | Subject | Re: UDMA Problem on VIA chipset - K7M motherboard |
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> From: "Robert A. Morris" <ramorris@mit.edu> > Date: Tue, 22 Feb 2000 14:56:33 EDT > Subject: Re: UDMA Problem on VIA chipset - K7M motherboard
> I do have the correct 80-conductor cable, counted the wires to make sure, > and the drives definitely do support up to UDMA mode 4. > > Is there any way to get this to work? There's a drastic speed improvement > with -X 66 (hdparm -t goes from not quite 5 mb/sec to just over 21 mb/sec) > and I'd love to get it to work. Thanks!
I have K7M with IBM-DJNA-351520 (15GB, UDMA/66) as hda and QUANTUM FIREBALL ST6.4A (6GB, UDMA/33) as hdb.
With old cable, I couldn't enable DMA (I got DMA error pretty soon) and with PIO transfers, I got the expected high CPU usage and lower performace. If I used both drivers at the same time (like when copying files from hda to hdb) I got sometime those "lost interrupt" errors, which prevented access to both drivers until reboot (both on 2.2.14 and 2.3.4x).
I got fed up with this and switched the cable to the 'correct' UDMA/66 cable. Everything seemed to work well for a time, but few days after I noticed that there is *data corruption* happening in older drive (hdb) when both drives are active the same time.
After iterating through several versions of kernels, kernel settings and disk positions I found out that the only combination that worked was switching by DVD-ROM drive (TOSHIBA DVD-ROM SD-M1212) to the same cable as the UDMA/66 drive _and_ using kernel version 2.2.14. With this combination, the DMA works even with simultaneous access as far as I have been able to find out.
If I use 2.3 kernels, I didn't notice data corruption, but the first time I accessed my DVD or CD-RW drives (now hdb and hdd) I couldn't access parts of my hard drives (hda and hdc), for example "fdisk -l /dev/hda" don't return anything since /dev/hda can't be accessed (/dev/hda1 can) and "fdisk -l /dev/hdc" returns partition 1 correctly (which is extended partition) but the line for first logical partition is corrupted.
As a side note, I noticed that when doing "hdparm -t /dev/hdX" for both harddisks at the same time got me about 3MB/s when they were in the same controller and 13MB/s and 9MB/s when they were in the different controller. So if you copy files between harddisks it seems that nowdays it really pays to have them in a different cable.
If someone wants to debug that wierd access problem in 2.3 I'm willing to experiment. If you want to ask me questions, you'd better cc: to me since I read kernel-list mails only when I have time and it might take several days until I see the mail from the list...
> Robert A. Morris <ramorris@mit.edu>
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