As you can see below, after enabling DMA, I experience a 24.9% improvement
in backup performance. !AWESOME!
Before DMA-on
Time elapsed 0:08:25.
Backup rate 18.8MB/min [28.9MB/min]
After DMA-0n
Time elapsed 0:06:19.
Backup rate 25.1MB/min [38.5MB/min]
Thank you very much Michael. What a great improvement :-)
Darrell
> -----Original Message-----
> From: Michael Weinberger [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, January 17, 2001 12:51 AM
> To: Darrell May
> Cc: [EMAIL PROTECTED]
> Subject: Re: [e-smith-devinfo] DMA + IDE harddisks
>
>
> On Tuesday January 16 09:45, Darrell May wrote:
> > Michael, don't think of it as a tape drive. How would you
> turn DMAon for a
> > hard drive? Same should apply as they are all just
> /dev/hdx where x =
> >
> > hda = primary master
> > hdb = primary slave
> > hdc = secondary master
> > hdd = secondary slave
> >
> > Regards,
> >
> > Darrell
>
> Darrell,
>
> ok, give it a try. At least for CDROM drives it works. But
> CDROM are random
> access devices. The instructions below only relate to _hard_drives_.
> Even if it works I don't expect a significant speed up, since
> the data transfer
> rates of tape drive in principle are low. But you can expect
> a decrease in CPU load.
> If it works for your IDE tape and you want DMA mode to
> persist, add the appropriate
> commmand somewhere in /etc/rc.d/rc.sysinit. Good luck!
>
> BTW, what type of IDE tape drive you are using (costs, media
> type+costs, capacity)?
>
> Michael
>
> (I decided to post to the list, since it could be useful to others)
>
> --- setting DMA mode for IDE hard disks ---
> hdparm -d1 /dev/hda
> enables DMA for the first IDE disk
>
> See "man hdparm" for more options. But be careful with -X34 or -X66.
> Usually these have no effect, but you could end up with a corrupted
> filesystem.
>
> If you want to use DMA permanently, edit /etc/sysconfig/hardisks and
> set USE_DMA=1.
>
> Do not use the hdparm -tT for benchmarking. The result are
> not very reliable.
> Better use bonnie++ or something similar.
> To be found at http://www.coker.com.au/bonnie++
> -------------------------------------------
>
