Veritas-bu

Re: [Veritas-bu] Netbackup 6.0 Backup Speed on HP Windows Blade

2007-08-09 10:27:55
Subject: Re: [Veritas-bu] Netbackup 6.0 Backup Speed on HP Windows Blade
From: "Austin Murphy" <austin.murphy AT gmail DOT com>
To: VERITAS-BU AT mailman.eng.auburn DOT edu
Date: Thu, 9 Aug 2007 09:55:27 -0400
On 8/8/07, tzurita <netbackup-forum AT backupcentral DOT com> wrote:
>
> All, have a question about speed.
>
> We are running the master server on a Windows C class HP blade with a dual 
> core 2.4 GHz Atholon CPU and 8 GBs memory.  Has two FC ports connected to:

> 12 - LTO3 Tape drives total
>
> Backups are not that fast and I am questioning why.  > Any ideas would be 
> great.
> ...   why such a vast difference betwen windows and solaris backups?  I am 
> just puzzled.  Help please.

> For Network Windows servers clients, we average just under 7 MB/sec
> Same server configuration for Solaris   33 MB/sec

> 15:18:25.355 [2720.5456] <2> write_data: waited for full buffer 63961 times, 
> delayed 80764 times

Your Windows clients are not sending data to the backup server fast
enough.  This causes the server to not send data to the tape drives
fast enough.  When tape drive are starved for data, they shoe-shine
and get really slow.

Speeding up your clients is a matter of tuning them for disk and
network I/O.
Concurrent access to a single disk is guaranteed to give you speed problems.
Here are some options:
- limit the client to 1 stream at a time.
- run the backups at a time when the disk is mostly idle.
- rearrange the RAID groups so they are all on separate sets of disks.
- put the RAID sets on separate controllers.
- make sure that you have lots of available network bandwidth.

If the server has millions of small files, you are facing a different
problem. That problem can be address with Flashbackup.

Regardless, if you can't get the client systems to serve up data fast
enough, then you can MultiPleX the jobs.   The tape drive doesn't care
if it gets 60 MB/sec from one client or 16, it just wants a fat pipe
full of data that it can continuously write to the tape that is flying
past the write heads at 4 meters per second.

Austin
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