On Tuesday 12 April 2005 14:23, Eric Dantan Rzewnicki wrote: >On Tue, Apr 12, 2005 at 01:50:15PM -0400, Gene Heskett wrote: >> On Tuesday 12 April 2005 10:50, Salada, Duncan S. wrote: >> >Actually, I'm not using a holding disk at all. I had no idea >> > that I could be shortening the life of the tape drive by not >> > using one. So, that's probably the source of my problem then? >> >> The idea behind the holding disk (which really shouldn't be on the >> same controller as the disk drive because of bus contention >> issues) is that if the drive is waiting on data and stops, it will >> not restart until the next file to be written is wholely in the >> holding disk, at which point the copy can then take place at the >> drives natural speed. > >My current amanda server lives on one big 1.4TB partition on an SATA >hardware raid controller. Copying from the holding disk to > file-tapes on the same device has so far been limited to about > 15MB/s.
Considering that the data has to go both ways up and down the cable, that may be about the practical limit. > This seems quite slow to me. Does amanda add any overhead > above a simple copy on the same device? An hdparm -t on this system > when it's idle gives around 58MB/s. > >I want to add a second SATA controller, fill up the remaining 4 > drive bays and move / and the holding disk to this separate raid. I > expect this set up will provide better performance. But, I want to > ask if anyone here has experience with a similar settup. Are there > pci bus limitations that would get in the way of the potential > benefits? other issues to consider? The stock pci bus is pretty well tapped out at 132 mhz, pci-x can quadruple that. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) 99.34% setiathome rank, not too shabby for a WV hillbilly Yahoo.com and AOL/TW attorneys please note, additions to the above message by Gene Heskett are: Copyright 2005 by Maurice Eugene Heskett, all rights reserved.
