backup job data rate

[Rick_Mallard]

I've got an MSL6000 library with ultrium 960 drives with LTO-2 tapes. When I do a backup I get roughly 450mb/min or 7.5 mb/sec compressed. I understand LTO-2 can theoretically get up to 30 mb/sec (native) and 60 mb/sec (compressed). If I run the HP LTT utility I get 42 mb/sec compressed. I am running Backup Exec v10d rev 5629, latest service packs, veritas drivers, firmware.

Why is Backup Exec so much slower and is there any way to tweak it?

Thanks,
Rick

[Ken_Putnam]

Local or network backups?

If network, what kind of network 100MB? 1GB? f you copy a large file from to the remote server, does the rate seem about right?

What kind of data? many small files or a few large files?

How badly fragmented is the disk the data is on?

[Rick_Mallard]

Local backup - local C: drive and D: fiber channel SAN. Lots of small files. Should be minor fragmentation only. The SAN defrags itself. Both get about the same data rate. We do use an OFO which adds time to the backup, but it should be much faster.

Here's from last night's backup - 124 GB in 6 hours

Original start time : Thursday, January 11, 2007 6:00:00 PM
Job started : Thursday, January 11, 2007 6:00:02 PM
Job ended : Friday, January 12, 2007 12:01:05 AM
Elapsed time : 06:01:03
Files : 549,153
Directories : 41,385Skipped files : 0
Corrupt files : 0
Files in use : 0
Byte count : 124,323,277,736 bytes
Job rate : 407.00 MB/Min (Byte count divided by Elapsed time for job)

[Rucha_Abhyankar]

Hi Rick,

Are you backing up any databases using the AOFO option?

If so please deactivate this option and then try the backup and verify if it helps.


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[Ken_Putnam]

From the Devices Tab, right click the drive \ Properties

What are the Block Size, Buffer Size and number of buffers?

Also, make sure that neither Single Block option is selected

[Wes_Miller]

adjust the HIgh Water Count and buffers in Vertias and Hp tools. From out of the box to the buffer adjustments I made I gained my backups finishing hours sonne each night. I backup 2 sql servers 1 exchange 2003 server and 18 file servers. Making adjustments to writes and buffers makes all the diffence on any hardware big hitter server with dual head librarys or even a desktop with 1 sata drive as a backup box

[Rick_Mallard]

I was using the defaults. The block size is 64K, buffer size is 64K, buffer count is 10, high water count is 0. Write single block mode is checked and Write SCSI pass-through mode is checked.

I was just reading up on it and getting ready to test with various settings. Anyone have suggestions as to what I should set these to?

Thanks,
Rick

[Wes_Miller]

well if you can tell me the speed of your network approx how many servers and data sizes I can give a suggestion or 2. The rule of thumb is how fast can you feed your backup system. 100 small files will always take longer than 1 large file. There is more overhead on small files. Sorry to be so vauge. It is hard to be specific if you dont have the specifics. out of the box defaults for my network were starting at 12:01am. The 2 jobs on 2 tape drives at the same time were finishing between 6-8am. After tampering with these settngs for a week or two I tuned the backup jobs to a degree they were finishing 4-5am.

I would uncheck single block mode and set the high wwater count to 2. Thisis just from what I have gathered from you so far.

The point is say you have 400,000 word and excel files in 250 folders on 1 server. If you have a really fast tape drive and you are not feeding it enough the tape drive will stop writing and wait for more packets. Then when it gets more that takes time to start writing again. If you leave the 64k block size and buffer more say 15. The high water count I beleive is how many it 64k blocks it will gather befor esending to the tape drive.

This is something you have to test on your own nobidy can give you good advice on this. you have to determine what kind of data you have how many servers to backup how many backup devices you have and last how many jobs you run. You want the flow of data to flow. Not to back up and keep stopping on the sending side waiting for th ok to send more or the tape drive saying I am done and wating for more. Thisis rule of thumb how you alter these settings. I have found that most people in this forum do not change this stuff. I have noticed a great decrease in the amount of time my backups take.

[Rick_Mallard]

Last night's backup was 124 GB in 6 hours. I backup one server (about 4 GB) and a ton of user data on SAN (about 120 GB in small files). As for the speed - it uses 2 HBA cards to access the SAN. The HBAs are 2 Gbps. The SAN uses all 15K fiber channel drives. The 960 ultrium-3 tape drives are in the SAN fabric. This server also has 1 GB NIC to access the rest of the network. The server is an HP DL380 with 1 GB RAM. I am using LTO-2 tapes..for now.

Any setting suggestions would be helpful.

Thanks,
Rick

[Wes_Miller]

try to set the size to 128k count 15 and the water 4. try this and compare.

Like Ken Putnam said "Also, make sure that neither Single Block option is selected " (NOT SELECTED)

MOST IMPORTANT OF ALL

Do not change to many things at 1 time. Dont mess with the job settings. Only the above until you have some numbers to comapre that are for the better. You will make a huge nightmare for yourself if you try to make to many changes. Make 1 change and test maybe 2 at most. This took me 2 weeks of making gradual changes for the better. Once you see a negitive change back to the most positive setting and that is progress that may lead from 20min to 1 hour faster backup time.

[Ken_Putnam]

"Write Single Block" bypases buffering. ie BacupExec reads a block of data writes it to tape, reads a block of data ...


This will absolutely KILL throughput.

I'd probably set buffer size to either 128K or 256K, but even as it is, it should be OK after de-selecting Single Block Write

[Wes_Miller]

I agree with Ken Putnam. This is what I noticed early on before I started tuning my veritas under my network conditions.

Just dont make to big of changes at 1 time. make a small change and do a selection and test it. If it has not lost performance try a little more. When you notice a decrease in performance roll back to the most positive settings.

[Rick_Mallard]

The settings for the tape drive didn't change the performance much. Deselecting the Single Block options only decreased the 6 hours backup time by 20 minutes...so I used HP LTT to try the Backup PreTest and found that using the Backup Exec tape drivers I get 9 mb/sec but using the HP tape drivers I get 23 mb/sec. A big difference. I will try to do more testing using the HP drivers...not sure if Backup Exec or the AOFO will work with HP drivers..?

Thanks for everyone's input. I'll let you know what I find. -Rick

[David_Homer]

Did you have any futher luck with this? I'm having problems that I have replaced an LTO2 tape drive library with LTO3 and see no performance increase. The librarys drives report tests of 75Mbs in L&TT however my drive throughput seems low from an MSA1500 SAN. I cant see how when shifting medium to large numbers of files that the MSA1500 can anywhere near keep up with the LTO3 drive unless I am missing something...?