If you have only 1 gigabit Ethernet connection to your DB server, you
won't be able to send data as fast as multiple LTO-3 drives NEED to
receive it.   Depending on the brand/model, each LTO-3 drive writes at
a MINIMUM of ~30 MBytes/Sec.  If you send data at a slower rate the
whole process gets bogged down while the drives "shoe-shine" to try to
match the slow data rate.    If the data compresses well you could
potentially send ~90MB/sec to a single drive.

I suggest limiting this backup job to a single drive and working on
optimizing the network speed and DB speed.

Multiple streams from the DB may increase the performance on that end,
but too many streams will probably cause local disk contention.

Austin


On 3/20/06, andrew.x.smith AT jpmchase DOT com <andrew.x.smith AT jpmchase DOT 
com> wrote:
>
> BTW, I think your maths is a bit wrong:
> 1.7TB of data it takes about 9 hours
>
>
> ((1782579.2Mb/9)/60)/60 = 55Mbytes a second = 440Mbits a second. This isn't 
> bad.....  Maybe ur MRTG is somehow limited to showing 100Mb as its maximum 
> value????
>
>
>
> "Atif Munir" <atif76 AT gmail DOT com>
>
> 20/03/2006 11:53
>
>         To:        "andrew.x.smith AT jpmchase DOT com" <andrew.x.smith AT 
> jpmchase DOT com>
>         cc:
>         Subject:        Re: [Veritas-bu] backup speed
>
>
> I am getting 100Mbits per sec.
>  I have only one client connect to the gigabit switch. and to backup 1.7TB of 
> data it takes about 9 hours. either i use 3 drives or 4.
>
>  My mrtg graphs shows that I could not use more than 100Mbits per sec.
>  I am using rman netbackup so the option of "Allow multiple data stream is 
> not highlighted but i am using 4 channels to backup data.
>
>  I have no idea where i can see NBU buffer size.
>
>  Regards,
>  atif
>
> On 3/20/06, andrew.x.smith AT jpmchase DOT com <andrew.x.smith AT jpmchase 
> DOT com > wrote:
>
>  Hi Atif,
>
>   Do you mean 100Mbytes or 100Mbits a second? Maximum theoretical through put 
> of 1000baseT is 1000/8=125MBytes a second so 100MBytes would be very good, in 
> contrast if you are getting only 100Mbits then that is failry poor - in this 
> instance please post some additional information about your config as this is 
> a very complex issue. Ie are the clients also connected on gigabit ethernet, 
> how many clients are there, what are your multiplexing settings, what are 
> your NBU buffer settings, etc, etc, etc
>
>                  cheers Andy.
>
>
> "Atif Munir" <atif76 AT gmail DOT com>
> 20/03/2006 10:57
>  Subject:        [Veritas-bu] backup speed
>
>  I have a gigabit ethernet. Recently i have installed 5 LTO Gen 3
>  drives. But I am not getting a very good speed. As a total I am
>  getting 100Mb/sec, and it take a lot of time to finish my backup.
>
>  Why I could not get a good speed.
>
>  Regards,
>  atif
>