On Tuesday 07 March 2006 14:58, FM wrote:
>Hello,
>
>Do I need a holdingdisk when I using hard drive backup ?
>
>I have a lots of iowait because of the copy from holding disk to
> virtual tape even if the holding disk is on internal SCSI drives and
> tapes are on an extrenal SCSI array (using sata drives)
>
I think the holding disk is still a good idea. It allows the "tapeing"
to proceed in the order that the individual DLE's are completed, and to
even have them juggled a bit in sequence in the event you are using a
priority string in your amanda.conf.
There may well be fragmentation effects to deal with when not using the
holding disk since then each DLE would get written in much smaller
pieces leading to more severe fragmentation issues. I am not haveing
that to a noticeable degree here, and I am using a large (24GB) holding
disk. However, when its time to e2fsck that disk, I haven't been aware
that fragmentation has ever been over 3%, and even that would be
preventable were it practical to make that many partitions, which it
isn't. All disks are ext3 formatted here.
The holding disk here is not, for obvious reasons, on the same spindle
as the vtapes, that would indeed be a "not recommended practice" I
believe.
It also serves as an emergency backup should something happen to the
vtapes disk, a rather important consideration IMO as you can effect a
repair of a failed disk before you actually run out of space, in my
case even for a 3 or 4 day holiday weekend. Install a new disk, format
it, do the mkdirs & labeling, make the link, and amflush it one days
worth at a time. No data of importance is lost since my dumpcycle is 4
days here.
>thanks !
--
Cheers, Gene
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.
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