Hi, Can anyone lucidly explain the whys and hows of this change? Is this a SCSI emulation thing or what? I know that Ubuntu 7.04 introduced this, which became a problem and broke a lot of people's /etc/fstab. If you were lucky enough to have drives referenced by their UUID, you were safe.
A server that we installed with 7.04 though came up with the hd as /dev/hda. When we did the 7.10 gutsy upgrade though it became /dev/sda (luckily the UUID was the reference, though the upgrade doesn't change the comments written in /etc/fstab. Anyway under 7.04 I had used hdparm to force on DMA as well as set the udma level from 2 to 4 - to optimise disk I/O performance. However hdparm now under 7.10 seems not to want to talk to /dev/sda properly. I get the following result that used to work [EMAIL PROTECTED]:~$ sudo hdparm -d1 /dev/sda /dev/sda: setting using_dma to 1 (on) HDIO_SET_DMA failed: Inappropriate ioctl for device [EMAIL PROTECTED]:~$ sudo hdparm -X udma4 /dev/sda /dev/sda: setting xfermode to 68 (UltraDMA mode4) SG_IO: bad/missing ATA_16 sense data:: 70 00 05 00 00 00 00 0a 00 00 00 00 24 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 HDIO_DRIVE_CMD(setxfermode) failed: Input/output error The problem is that I notice that I get a heck of a lot of CPU WAIT time happening when doing I/O to the disk, presumably because DMA isn't working. (BTW I looked at "sdparm" but it seems to be a totally different animal) I have added a comment to https://bugs.launchpad.net/bugs/96693. It seems that there is no definitive technical description of this migration. I sort of wonder how thoroughly it has been thought through or tested. Anyone here care to comment? Regards, Martin Martin Visser -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html