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Throughput

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Mike Le Master
Contributor

Throughput

As I write this at 11:00 am my nightly differential backup of approx 40 GB is still running (about half done) from last night. Throughput is 30 MB/min. I am going to have to kill the job so I can run my full weekend backup of approx 200 GB.
I have a P200 Proliant 2500 with 320 MB/RAM with Windows 2000 SP3 running Backup Exec v8.6 onto an Overland LoaderXpress LXL4110. Backup Exec is the only thing running on this server.
I use HP C5141F tape exclusively.
I have worked with Backup Exec and with Overland to tweek the software and hardware to get the best throughput. The only thing left is the media (unless anyone can come up with a new idea for the software and hardware).
I have noticed that when soft write errors on the media are low, in the range of 25,000 or so, my throughput goes to 110 MB/MIN, which is what Overland states I should get. However, when the soft write errors climb to several hundred thousand (the tape running now has 239,000 soft write errors), throughput slows so much that I cannot finish a backup.
If soft write errors be the problem, short of retiring the tape, is there a workaround?
2 REPLIES
Marino Meloni_1
Honored Contributor
Solution

Re: Throughput

Hello,
I do not know your tape device, but as you are using DLTiV cartridge I assume you could use a DLT8000.
this tape have a througput of 6 MB/S that means 360 MB/Min (Not compressed)
If your drive is a VS80 , ........3 MB/S = 180 MB/Min =21 gb/hour
Your value goes from 110 MB/Min down to 40 MB/Min .
You have to investigate a few things:
Run L&TT (if it support your Tape Device) in order to analyse the device itself, you will be able to run some test like Read/Write or Media Validation that will confirm you that you have poor tapes or poor Heads. this tool will also look in th DLT log for soft errors or Bugcheck. (soft errors are usualy errors corrected by the Tape device itself and can be caused by poor tape or poor / contaminated Head)
You also need to analyse the path you use in order to perform your backups, did you backup through the Lan or did you backup localy?, You can use some tools in order to check you server/path performance One is called PAT (performace assestment tool) and can be downloade on the HP site

marino
Marino Meloni_1
Honored Contributor