Michael,
it would help if you told us what your SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS
values actually are and how you calculated these values.


James



On Mon, 30 Sep 2002 14:55:47 -0500 "Niehaus, Michael T." <MTNiehaus AT 
marathonoil DOT com> wrote:

> 
> I've been trying to tune backups running on a particular media server in our 
> environment and am not making much progress.  I've modified the 
> SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS parameters (with local/SAN attached 
> tape drives) but it doesn't seem to make much difference.  From my last test, 
> I saw the following messages in the "bpbkar" log file:
> 
> 3:13:41.250 PM: [2780.2308] <4> tar_backup::OVPC_EOFSharedMemory: INF - 
> bpbkar waited 4198 times for empty buffer, delayed 6071 times
> 
> That seems to imply that I don't have enough buffers, but from the "bptm" log 
> file I see this:
> 
> 15:13:41.343 [1976.1984] <2> write_data: waited for full buffer 1608 times, 
> delayed 1951 times
> 
> which implies that "bpbkar" couldn't fill the buffers fast enough.  So which 
> is it?  In this case, I was doing a very simple, best case performance test, 
> backing up a single 4.2GB data file.  I'm consistently getting about 13MB/sec 
> to a Seagate LTO tape drive over fibre channel.  Is that the best I can hope 
> for?  And why wouldn't I see all the delays in "bptm" (if the tape drive is 
> the bottleneck) or all in "bpbkar" (if the disk is the bottleneck)?
> 
> This is a NetBackup 4.5 media server, running Windows 2000 SP2, with plenty 
> of memory and CPU capacity.
> 
> Thanks,
> -Michael
>