04-08-2014 12:35 PM
The Setup is as below:-
1) Tandberg Tape Library L120+ with 4*HP HH LTO-6 tape drives.
2) IBM x3650M4 Media server with 8 GB RAM, 3* 300 GB HDD with one Dual port 8 Gbps Emulex HBA.
3) Backup is for Teradata application. The data from multiple LAN clients moves to this media server which moves the data to tape library through SAN switch.
4) All 4 tape drives and 2 ports of Emulex card of media server are put in the same zone of SAN switch.
We tested backup and were able to achieve 100 MBPS on a single LTO-6 drive and backup on all 4 LTO-6 drives is not going beyond 140 MBPS.
The team has been doing testing for past 10 days and has tried changing various network parameters, done Gigabit port teaming, tried direct SAN backup using BCV but the max throughput from the library is 140 MBPS only.
Appreciate suggestions !!
04-08-2014 02:50 PM
Have you tuned Netbackup buffers (NUMBER_DATA_BUFFERS/SIZE_DATA_BUFFERS) ?
See : http://www.symantec.com/docs/TECH18422
100MB/sec sound like the speed of 1GB ethernet or do you read data off a BCV volume.
04-09-2014 01:14 AM
You're unlikely to go beyond 140Mb/s any way. The maximum throughput on a LTO6 is 160Mb/s so you're only missing 20mb/s MAXIMUM of the total possible for these types of drives. Never expect to get to the limit.
Factor in Network and disk speeds (for reading) you will get a backup of the slowest part of the whole process.
Have you tried using bpbkar -nocont /backup_selection and timing it to find out who quickly your backup is able to read the backup selection?
04-09-2014 01:44 AM
We get 140 MB/s with all 4 drives also.
Can their be any potential limitation that tape library can bring in this setup as the overall backup is not going beyond 140 or 150 MB/s in the library ?
04-09-2014 03:37 AM
Try to measure maximun transfer speed from media server to each tape drive by taking large flat file on the media server or using GEN_DATA directive.
if you get more transer in this test, bottleneck may reside in network or client.
04-09-2014 07:24 AM
That;s a good idea. Try backing up a large flat file as suggested, directly on the media server that has the drives zoned - still only 140mb/s ?
04-09-2014 11:58 AM
As you said ....
"IBM x3650M4 Media server with 8 GB RAM, 3* 300 GB HDD with one Dual port 8 Gbps Emulex HBA."
8GB RAM will be enough for Media server ?
compare to LTO6 , 8gigs dual port HBA,
04-10-2014 12:30 AM
Thanks for your comments !!
We finally managed to surpass the 140 MB/s and achieved 240 MB/s by firing the backups from 2 media servers simultaneously.
The application is not able to pump sufficient data which we were testing earlier !!
04-10-2014 01:58 AM
How are you getting 240MB/s when LTO6 is only capable of 160MB/s (uncompressed)?
Are you using compression?
04-10-2014 03:40 AM
4 tape drives *160 = 640.
I think the 140MB before was a total of all 4 drives combined. The user now see 240 combined of all 4 drives
Or am I totaly wrong ?
04-10-2014 08:44 AM
Yes, this is from all 4 drives put together.
04-11-2014 01:35 AM
Then you got a long way to go. What Netbackup buffer size has you configured ?
You can see the value in the activity monitor - detailed status.
Something like this will show. Default value is 30 buffers - this is way to low. By adding more buffers you should see writing performance rise like a rocket.
04/10/2014 18:02:27 - Info bptm (pid=3521) using 524288 data buffer size
04/10/2014 18:02:27 - Info bptm (pid=3521) using 256 data buffers
04-11-2014 01:43 AM
Nicolai (aka 'The King of buffer tuning' ) speaks 'wise words' ... ;0)
04-11-2014 04:45 AM
Yup, 240Mb/s across 4xLTO6 is actually fairly poor. I say fairly and not VERY!
04-11-2014 07:13 AM
Try Yasuhisa suggestion: GEN_DATA : removes disk i/o from the equation altogether.
I have LTO4 and you _can_ get max drive perfomance, that is a fact from my perspective at least.
04-14-2014 04:52 AM
I support the GEN_DATA suggestion. Here is a tech note about GEN_DATA
Please note GEN_DATA is only supported on Solaris and Linux. No Windows support.
05-08-2014 12:40 AM
I might have missed something, but what are the net card configuration in the media servers ?
With 4 times 160 MB/sec for the tape drives, you would need at least 5 Gbit to sustain the tape drives
Personally I would go for 10 Gbit net cards as I have seen a lot of strange stuff with teaming/trunking
if you cannot use gen_data, iperf for windows can give an idea of how much bandwidth you have between the clients and the media servers