Veritas-bu

[Veritas-bu] NBU Data Buffer sizes

2001-05-08 13:09:10
Subject: [Veritas-bu] NBU Data Buffer sizes
From: AhrensJ AT psi DOT ca (Jason Ahrens [ahrensj AT psi DOT ca])
Date: Tue, 8 May 2001 13:09:10 -0400
I am assuming this is on the media server? Or does it matter? Or should it
be on both? (assuming separates master/media servers)

As a check on my own math, I have StorageTek 9800 drives. 10MB/s theoretical
maximum write speed, 256k block size.

At some point in the past, I set
/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS to contain 262144 (256k)...

I did this on the master server. I expected restores to break for the 'cut
over' time after I increased blocksize from 64k to 256k, but it did not...
(should it have? Does this mean I'm still using a 64k block size?)

Now, using the below system, I should set
/usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS to be
(10MB/256k)=(10485760/262144) which would give me 40 buffers (per drive)...


Jason

> -----Original Message-----
> From: Marelas, Peter [mailto:MarelP AT AUSTRALIA.Stortek DOT com]
> Sent: May 7, 2001 20:05
> To: 'Tim Allen'; Veritas-bu AT mailman.eng.auburn DOT edu
> Subject: RE: [Veritas-bu] NBU Data Buffer sizes
> 
> 
> Tim,
> 
> I tend to tune the buffers based on the maximum theoretical throughput
> of the tape drive in question.
> 
> However to do so you need memory on the server.
> 
> You've got it set to 16 and 64512 respectively.
> 
> Therefore Netbackup will use 16*64512=1032192 bytes per tape drive
> in use.
> 
> Assuming the maximum theoretical throughput of a drive is 6MB
> I would set SIZE_DATA_BUFFERS to the tape drives optimum block
> size (usually 64k, 128k or 256k).
> 
> Lets assume its 64k (65536), divide 6291456 bytes (6MB) by 
> 65536 bytes (64k)
> you
> get 96 NUMBER_DATA_BUFFERS. That should be the optimum setting.

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