Query on NDMP Backup speed

[Stiva]

Hi Team,

I have one query regarding NDMP backup speed. As mentioned in my earlier Forum Discussion we are using Direct NDMP backup. I have increased Data Buffer size to 256Kb & Number data buffers to 32.

Suppose there are 3 streams run at a time of single NDMP filer, Do the backup throughput divide among the 3 streams or per stream have its own speed.

All 3 streams use same tape for backup. How it affect the Backup througput? I have done some R&D from my end still I need experts advice...:)

Thanks in advance!!!

[Marianne]

Each stream will list throughput for that stream only.

So, for 3 streams, you need to add up Kbytes/sec seen in each stream.

If you have bptm log enabled on NDMP media server, you will see overall throughput at the end of multiplexed backup.

To understand what the effect is for 3 streams to a single tape, you firstly need to look at throughput of single stream to single tape and compare with tape drive capability.
If, for example you get 30 Mbytes/sec on a single stream to a single tape and about 90 Mbytes/sec when 3 streams write to a single tape/drive, then all is good. You want to keep your tape drive streaming at a reasonable speed.

If you get close to 100 Mbyte/sec on a single stream to a single tape, there is no point to multiplex. 
Write each stream separately (single stream to single drive).

[Pritesh_Pisal]

I hope you have SIZE_DATA_BUFFERS_NDMP in place if you are using tape deivce.

Take a lookt at the TN

http://www.symantec.com/docs/TECH51967

[ontherocks]

Hi Stiva,

Create SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS file as shown below ::

/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS

Put the value 262144 in this file

/usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS

Put the value 128 in this file

[jim_dalton · Accepted solution]

You cant MPX with direct ndmp, by the way, unless its a recent development.So from that viewpoint alone I cant see this being a real example, is that correct?

If so, what is the real actual driver that has raised your question?

If its just throughput, then as per other answers, you add them up. Performance is an entirely different issue.

Jim