how many devices we can have on one media server

[T_N]

Hi All;

Can someone tell me :" how many devices we can have on one media server " Thank you.

[mph999]

If you mean tapestries, then as an approximate answer, taking LTO5 type, if you want to write to all drives at the same time above streaming speed, then about 5 or 6. 

If they will not all be used at once then I would have more than 15 personally, it all depends on other factors, how many mediaservers, are the drives shared.

I had one case with 35 media servers all  sharing something like 50 drives, + some media servers had a few not shared. In a word, it didn't work, just too much load.  Reduced it to 16 per server and it was fine, not that you could run16 at once though and be to meet the required throughput to stream.

The.way to get an exact answer iswork out the through put of the HBAs, and see how many drives you can connect to each port, and take into account the backbone of the media server.

[T_N]

we are using VTL with DXI6702, thank you.

[mph999]

For a VTL, the streaming speed is not important, so you could run for VTL tape drives than 'real' drives.

Lets look at this another way, how many devices are you thinking of putting on the media server.

[Nicolai · Accepted solution]

There is no "fixed" number as such in my view. Whenever the general performance starts to drop, you have overloaded the servers.

One example for illustration only:

1 drive 250MB/sec        Combined speed 250

2 drives 240 MB/sec     Combined speed 480

3: drives 200MB/sec   Combined speed 600 

4 drives 140 MB/sec     Combined speed 560

5 drives  80 MB/sec     Combined speed  400

In this scenario its pretty obvious the sweet spot is 3-4 drives. But its very individual from media server to media servers. Distribution of tape drives  amount fibre channel HBA, network and SAN load all contribute to the maximum possible load.

Virtual tape drives are in reality disk, so the "shoe shining" effect does not apply.

If not already done so configure NUMBER_DATA_BUFFERS/SIZE_DATA_BUFFERS in Netbackup. How to do is documented in the http://www.symantec.com/docs/DOC7449

Configuration of buffer is the number one teak in Netbackup. Go for 262144 in SIZE_DATA_BUFFERS (default value) and 256 or larger for NUMBER_DATA_BUFFERS