On Tuesday 07 March 2006 15:41, 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)
>
I'm not sure the latter 2 will reduce the loading on the server. It
really should be capable of keeping up with 20 clients unless the
network is some old slow protocol or there simply isn't enough iron in
the server to do it. After all, all it should be doing is moving data
to the holding disk from the network, and thence to the tape, neither
of which, even combined, should make a 400mhz K6 even break a sweat
unless its also doing the compression duties for itself as a client at
the same time. There is not a not you can do about that except add cpu
horsepower & memory. To put that into perspective, this box, an
xp-2800 athlon, is also backing up my firewall, a 500mhz k6-III, with
the clients all doing their own compression. I have 48 DLE's, 12 of
them on that slow box. On nights when level 0's are being done, they
are the last 37-48 in the order. On nights when its all level 1, that
boxes order ascends to 5 thru 16.
In the case I had 20 clients, I would make sure those 20 clients all
have unique spindle numbers for every physical disk, and then reset the
inparallel to 20 and the maxdumps to 20, which means that all 20
clients can then work at their own pace. The holding disk will fill up
if the tape can't handle it, but more holding disk is a commodity item
these days with 300GB ATA Seagates with a 5 year warranty at about $130
(after an $80 rebate) at C.City.
This is not intended to be gospel, just a suggestion, but thats how I'd
approach it till I found differently by experimental results.
>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.
--
Cheers, Gene
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.
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