Networker

Re: [Networker] Target sessions on drives not working properly.

2003-12-30 15:32:41
Subject: Re: [Networker] Target sessions on drives not working properly.
From: Kent Holloway <Kent.Holloway AT ONVOY DOT COM>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Tue, 30 Dec 2003 14:32:34 -0600
The session count is not usually set that high.
I had it set at 6 before and could not figure out why I could not get more than 
4.
I upped the count to 20 just to be sure I wasn't hitting some limit I didn't 
know about.

I have other drives on this same server and they seem to load up at least the 
number of target sessions that are set for each drive. (DLT7000 are the other 
jukeboxes in my config and they are set at 6 target session)



-----Original Message-----
From: Faidherbe, Thierry [mailto:thierry.faidherbe AT HP DOT COM] 
Sent: Tuesday, December 30, 2003 1:47 PM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: Re: [Networker] Target sessions on drives not working properly.

15-20 Sessions a device ! my God ... 
Yes, I know, having tape device streaming but ....

Let me just to remember one of the first backup law :
 "Fast Backups, Slow recovers"

Having a multiplex factor set so high, in case of a recover,
you will have to perform far more tape read operations
in order to demultiplex data have all of the clent's data 
recovered back to disk over lan.

A strong advice for tape devices is to never go higher 6.
I am always using 4-6 or in some very rare case, 8 but
never 15 or above !

Have once a try to perform a recover and monitor the
recover time with (effective) tape parallelism set to 4 and 15.

Also remember session per device is a load balancing factor, 
not limitative one.
So, depending of pool settings, you can go higher than 15/20
although you set the parallelism to 15 with all of the recover
consequences it may have.

You should consider DDS or static library sharing.
In any case, you will never saturate 4 SLDT device with lan base
backups from 4 clients.

If DDS or shared lib is not an option, go for disk staging and
then migrate locally from disk to tape, with 4 session a device.
You will get the max speed.

HTH,
Th

Kind regards - Bien cordialement - Vriendelijke groeten,

Thierry FAIDHERBE

HPCI - Storage & Server Integration Practice 
Tru64 Unix and Legato EBS Consultant
                                   
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-----Original Message-----
From: Legato NetWorker discussion [mailto:NETWORKER AT LISTMAIL.TEMPLE DOT EDU] 
On Behalf Of Kent Holloway
Sent: mardi 30 décembre 2003 20:17
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: Re: [Networker] Target sessions on drives not working properly.

David,
 Thanks for checking, I forgot about that option but after checking it
is currently set to '60' for the group I am testing with. I am starting
the group via the command line like so 'savegrp -l full groupname', I
have also tried just 'savegrp groupname' and get the same results.

Librado,
 I have no other saves running during my test right now. The server is
idle at the moment.
I just have 'All' listed in the savesets for the clients but when they
save the 'All' is broken out into 4-5 savesets and shows up as each one
backing up. I get up to 4 savesets and no more per tape drive. I have
even had 2 saves from 2 different clients on one drive but when the 3rd
saveset from either of the clients or another client appear it wants to
load an additional tape.

The big problem is 4 savesets doesn't load up my SDLT220's and I end up
writing at a much slower speed than I am able to attain.

Thanks again for all the help.

 

-----Original Message-----
From: David E. Nelson [mailto:dnelson AT ni DOT com] 
Sent: Tuesday, December 30, 2003 12:02 PM
To: Kent Holloway
Subject: Re: [Networker] Target sessions on drives not working properly.


Hi Kent,

Did you check 'group parallelism' it's a hidden option under groups.
Also, are 
you starting the group via the GUI?

Regards,
        /\/elson

On Tue, 30 Dec 2003, Kent Holloway wrote:

> I have 4 SDLT 220 drives on a StorageTek L180, I am trying to load up
1
> drive with 10-15 savesets.
> 
> I have a group with 4 clients in it each with 4-5 savesets. 
> Clients are each set at Parallelism of 4.
> Server Parallelism is 48.
> Each Tape drive is set at Parallelism of 20.
> 
> When I run the savegroup I only get 4 sessions per drive.
> 
> I have stopped and restarted all Networker processes just in case and
> that has not made any difference.
> 
> Backup Server: Solaris (Sparc) 8 / Networker 6.1.4 Network Edition
> Clients: Solaris (Sparc) 8 clients running Networker 6.1.3
> 
> Any idea as to what I'm missing here?
> 
> Thanks.
> 
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