Why is my tape drive slow?

chrisl456 · n00b Joined: 12 Jan 2004 Posts: 18

Hello forum,

I'm trying to figure out why my Exabyte VXA-2 drive isn't performing up to spec (12 MB/s, see http://exabyte.com/products/products/get_products.cfm?prod_id=400&product=VXA%2D2%20Packet%20Tape%20Drive). I'm using tar like so to put data on it:

Sloden · Posted: Tue May 03, 2005 8:26 am Post subject:

I realize that this isn't the case, but if the speed were 12 mega 'bit' a second you'd be right on track. You might wanna try "hdparm -tT /dev/nst0" to estimate your drive specs. As i have no idea if hdparm really works with tape drives i take no responsibility whatsoever if your box decides to self implode.

Good luck.

Try this:
https://forums.gentoo.org/viewtopic-t-330882-highlight-tape.html
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chrisl456 · n00b Joined: 12 Jan 2004 Posts: 18

Yep, I've confirmed that the drive is supposed to be writing at 12 megabytes per second (PDF:http://www.exabyte.com/support/online/documentation/drives/10095413.pdf, see ch. 8).

Also, restoring off the tape takes so long that I've never really had a successful restore!

Anyone have any ideas what could be wrong?

Thanks!
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-chris

Cintra · Advocate Joined: 03 Apr 2004 Posts: 2111 Location: Norway

Hei

Did you read through this?
http://www.exabyte.com/support/online/kb/display.cfm?id=794

mvh

edit: to get the best out of the device you have to keep it streaming.
question is how fast are your disks transferring, the good old hdparm -Tt /dev/hdx check might be a starting
place. lot of good info here too http://64.233.183.104/search?q=cache:d-uUxUHYAV0J:www.exabyte.com/support/online/documentation/whitepapers/optimizing.pdf+Exabyte+VXA-2+poor+performance&hl=no&lr=lang_da|lang_en|lang_no|lang_sv&client=firefox
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Drunkula · Posted: Tue May 03, 2005 5:33 pm Post subject:

Instead of using nst0 can you use nht0 instead (the non-scsi-emulated ATA tape device) and see if that makes a difference. IIRC nht0 would be the correct counterpart.