On Fri, Jan 28, 2011 at 03:00:17PM -0700, Charles Curley wrote: > Oops, I should have sent my reply to the list. > > On Fri, 28 Jan 2011 16:35:05 -0500 > Joe Konecny <[email protected]> wrote: > > > On 1/28/2011 2:11 PM, Charles Curley wrote: > > > For now, with 100 GB of data going to a 1 TB hard drive, you can > > > probably back up to that hard drive. But not for long. Two caveats: > > > > > > * Having your data, holding disk, and vtapes all on the same drive > > > will result in lots of disk drive thrashing. Ideally, have each on > > > their own drive. Short of that, eventually go to a separate drive > > > for the vtapes. > > > > My data would be on a different server than the vtapes. Does a > > holding disk make a big difference if you are using vtapes? > > Yes. vtapes emulate a tape to the point that amanda won't write to them > in parallel, just as it cannot write to a tape in parallel. A holding > disk lets amanda always have one or more DLEs ready to go to the tape. > While shoe-shining obviously isn't an issue with vtapes, that one DLE at > a time requirement is a bottleneck. > > There is an effort to allow one configuration to write to multiple tape > drives (including vtapes), but I don't know its status. That might move > things along fast enough to reduce the need for a holding disk, but I > haven't played with it. >
Charles, do you find the use of a holding disk to be a major drawback? The time to backup my small network is about 2 hours but the dump time is almost 3x the wall clock time. Yet the total time for "taping", i.e. holding disk -> vtapes is only 16 minutes. In my environment there is little need for multiple vdrives despite its sequential nature. Jon -- Jon H. LaBadie [email protected] JG Computing 12027 Creekbend Drive (703) 787-0884 Reston, VA 20194 (703) 787-0922 (fax)
