01-31-2014 02:20 PM
We're using a Netbackup 5230 Appliance connected via 8Gb fibre to an HP MSL 8096 LTO 5 tape library with 4 drives. I've read many posts recommending leaving the buffer size as default:
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02-04-2014 05:33 AM
If you have not modified the default buffer sizes you will need to do so - but as the one can affect the other make sure you do both
From the CLISH of the appliance follow this process:
Go to the Settings menu and then type:
NetBackup DataBuffers Number Show
NetBackup DataBuffers Size Show
to see what they currently are. To change them use:
NetBackup DataBuffers Number Disk 64
NetBackup DataBuffers Number Tape 64
NetBackup DataBuffers Size Tape 262144
NetBackup DataBuffers Size Disk 1048576
The disk setting is up to you but generally works well - as do the numbers used above
Hope this helps
01-31-2014 02:46 PM
If the backup where made with a 64K blok size they will duplicate as 64K blocksize. New backup made with 256K will duplicate as 256K.
Can this be the case ?
By the way: Set NUMBER_DATA_BUFFERS & NUMBER_DATA_BUFFERS_RESTORE to 256 as well.
02-03-2014 01:11 AM
Are you using tapes that have been used in another system that did not use the 256kb block size? (or this system before you changed the DATA_BUFFER settings)?
When a tape is written using a particular block size that gets written to its tape header and whenever that tape gets used it will use the original block size.
To clear this setting you need to label the tape.
To test if this is the case just select the unassigned tapes that are ready to use for the next duplication - select to label them but uncheck the Verify box - they will then be relabelled using your current 256kb block size and should then use that from then onwards
It does mean labelling all of you tapes before they get re-used (once they are unassigned - everything on them expired)
Worth a test
02-03-2014 07:49 AM
The buffer settings on the appliances have not been modified. The original backup images are using the default buffer settings:
All tapes being used are brand new, never been used before. However, I will try taking the next scratch tape and manually labelling it with the verify unchecked.
Thanks,
Aly
02-04-2014 05:33 AM
If you have not modified the default buffer sizes you will need to do so - but as the one can affect the other make sure you do both
From the CLISH of the appliance follow this process:
Go to the Settings menu and then type:
NetBackup DataBuffers Number Show
NetBackup DataBuffers Size Show
to see what they currently are. To change them use:
NetBackup DataBuffers Number Disk 64
NetBackup DataBuffers Number Tape 64
NetBackup DataBuffers Size Tape 262144
NetBackup DataBuffers Size Disk 1048576
The disk setting is up to you but generally works well - as do the numbers used above
Hope this helps
02-04-2014 08:03 AM
Thanks for your help. I configured the tape size using the touch files, which seemed to work.
The settings currently show as follows:
02-04-2014 08:18 AM
Also, we are using AIR with a second identical appliance. Do these settings need to be configured there as well, or will AIR be unaffected?
02-04-2014 09:08 AM
That looks fine - the one that is just buffers refers to tape (SIZE_DATA_BUFFERS)
AIR will not be an issue in relation to these but it is nice to have both appliances the same.
02-04-2014 09:13 AM
Great, thanks for your help. One last question. To verify that this is getting better performance, do I just watch the "02/04/2014 10:56:36 - Info bptm (pid=23368) waited for full buffer 5460 times, delayed 17187 times" line in the logs to ensure it drops?
02-04-2014 09:34 AM
The bptm logs are good for this plus one other location that is really useful for duplications...
Just run an All Log Entries report from the Admin Console for a period before you changed them and a period afterwards
You will see entries something like successfully wrote (duplicate) copy 2 at xxxx MB/s
It is about the only place you see duplication throughputs in clear text - you can export it to a text file, import into excel - sort by message and then have a look at the rates you are getting when duplicating to tape
This will let you do a comparision
02-05-2014 02:06 PM
before:
Fri Jan 31 14:37:37 EST 2014 Info 11875 Backup successfully wrote backup id client_1390261365, copy 2, fragment 1, 70248368 Kbytes at 33861.979 Kbytes/sec
After:
Wed Feb 05 11:39:27 EST 2014 Info 13458 Backup successfully wrote backup id client_1390609931, copy 2, fragment 1, 70282749 Kbytes at 62421.065 Kbytes/sec
So looks much better, thanks.
However, although the FT buffer settings were set as above, this morning, I see that a SAN client backup failed with the following in the logs:
02-05-2014 02:34 PM
Looks like some of it is down to the O/S : http://www.symantec.com/docs/TECH62007
http://www.symantec.com/docs/TECH206660
http://www.symantec.com/docs/TECH181285
The last 2 links relate to appliances but as usual there are lots of variables - I would try 32 buffers of 256k (262144) first and see how that goes
02-06-2014 07:42 AM
Thanks Mark.
256k seems to work well, but as per one of the docs you sent, plus the Netbackup Tuning guide, which says:
Note: It usually does not improve performance to increase memory buffers to anumber that is significantly more than the SAN Client Fibre Transport default(16). Such an increase usually causes the majority of the buffers on either theclient or server side to be empty.
02-06-2014 10:22 AM
No - that does sounds OK to me if that is Symantec view - if it is working OK with 32 then try 16 to see if it makes any difference
But which ever works for you best is the one to go for.