Amanda-Users

Re: holding disk when using HD backup ?

2006-03-07 15:57:44
Subject: Re: holding disk when using HD backup ?
From: "Ram \"TK\" Krishnamurthy" <tk AT zmanda DOT com>
To: FM <dist-list AT LEXUM.UMontreal DOT CA>
Date: Tue, 07 Mar 2006 12:57:49 -0800
Ok, I re-read the original as well as this post again.
If you are copying multiple DLEs's and you want to be in a single image
then holding disk is definitely needed - whether you are flusing to an actual tape or vtape.

And the added fact that you have anothe copy, should the actual back up fail.

Performance improvement without holding disc is likely to happen when you have only a few [more like 1 or 2], dle's.

Thanks
tk


FM wrote:
Sorry if I was no clear enough :-)

My setup :
1 amanda server with virtual tape (hard disk)
20 remote clients

My problems : my server is overloaded during the backup. I suppose that
I can play with those parameters to  reduce the load :
compress parameter should be client and not on amanda server
reduce inparallel (now 10)
reduce maxdumps (now 4)

thanks!


Ram "TK" Krishnamurthy wrote:

Jon
My comment was for backing upto disks. And I mis-read the original
post that he was backing to tape. You are correct that holding disk is
key for dumping multiple dle's.


tk

Jon LaBadie wrote:

On Tue, Mar 07, 2006 at 12:07:25PM -0800, Ram TK Krishnamurthy wrote:


You generally do not use holding disks when backing up to disks.

tk

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)



Why not Ram?  Without a holding disk only one client DLE can
be dumped at a time.  The holding disk is to allow multiple
DLEs to collect simultaneously, only transfered to "tape"
when complete.  Without a holding disk the DLE must be
dumped "directly to tape" eliminating all parallelism.



--


Ram "TK" Krishnamurthy

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