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Re: DMA on SATA disks?

On Fri, Feb 10, 2006 at 06:45:22PM +0100, martellif@supereva.it wrote:
> Mine doesn't work, maybe hdparm that comes with sarge doesn't handle yet 
> such kind of drives?
> root@darkstar:~# hdparm -I /dev/sda
> /dev/sda:
> HDIO_DRIVE_CMD(identify) failed: Invalid argument
> root@darkstar:~# hdparm -i /dev/sda
> /dev/sda:
> HDIO_GET_IDENTITY failed: Invalid argument

I believe it may be kernel version dependant.  There has been work
lately in 2.6 for supporting S.M.A.R.T. and other such things on SATA
and 2.6.8 certainly did not do it.  This may be related.

> Strange but it works with -tT switch:
> root@darkstar:~# hdparm -tT /dev/sda
> /dev/sda:
> Timing cached reads:   2688 MB in  2.00 seconds = 1340.85 MB/sec
> Timing buffered disk reads:  170 MB in  3.03 seconds =  56.17 MB/sec
> root@darkstar:~#

-t and -T have always worked on any block device.

> Here mount output
> root@darkstar:~# mount
> /dev/sda5 on / type reiserfs (rw,notail)
> proc on /proc type proc (rw)
> sysfs on /sys type sysfs (rw)
> devpts on /dev/pts type devpts (rw,gid=5,mode=620)
> tmpfs on /dev/shm type tmpfs (rw)
> usbfs on /proc/bus/usb type usbfs (rw)
> /dev/sda10 on /mnt/disk type ext3 (rw,noexec,nosuid,nodev,user=frank)
> /dev/hdd1 on /mnt/hd type ext3 (rw,noexec,nosuid,nodev,user=frank)
> Searching with apt-cache I found blktool package, does anybody know if 
> it is a valid replacement of hdparm.

Not sure what it does.

I find -t is a good way to check if DMA is on or not.  Speed under 5MB/s
and DMA is off.  Speed over and DMA is on.  If I get 50MB/s on my SATA
drive, I know it is working as it should.

Len Sorensen

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