Paula

Howard Martin wrote:

I think the hbn device will still compress you might get a bit more on using just bn.

A 800 GB native tape when not using compression won't show a lot different to 800 GB on it under Networker as it reporting how many bytes were sent to the drive. Networker doesn't say the the 792GB represents say 3TB of data and therefore the tape contains 3TB.

Hope that makes sense.

On Thu, 6 Mar 2008 12:04:39 -0500, Paula Ehn <pehn AT CC.UMANITOBA DOT CA> 
wrote:

Hi gang!

Is anyone out there using LTO-4 tape drives without hardware compression?

I'm trying to figure out if I have a problem with the tape drives,

Networker

or the drivers/patch in Solaris.

We use Networker's compression on the client side so that we are
transferring a smaller amount of

data over our LAN to the backup server. To avoid compressing the data

twice,

we have compression turned
off on our LTO-4 tape drives. For expample, we use /dev/rmt2hbn instead
Problem is I'm seeing
consistantly that only 792-794GB are being put onto each tape.

We use to use this same configuration when we used AIT-1 then later AIT-3
tape drives and saw a wild spread in the amount of data being put onto a
given tape. For AIT-3 it was anywhere from 120-320GB depending on how
compressable the data was.
For LTO-4 I'm expecting a similar spread but not less than the native
capacity on the tape which is 800GB. I expect it to
read better then 1TB on a tape at least.

Any ideas?

Networker 7.2.2 Jumbo (server and client)
Solaris 9
STK SL500 library with 4 HP FC LTO-4 tape drives.

Devices in Networker set to LTO-3 (LTO-4 option not available in 7.2.2)

and

default capacity set to 1600GB.

We are planning to upgrade first the server this year to Solaris 10 and

then

Networker to 7.4.x but not until summer.

Thanks!
Paula
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| Paula Ehn  VE4MHZ/VE4HZ                    Room E3-628 EITC     |
| Unix System Administrator             pehn AT cc.umanitoba DOT ca |
| Academic Computing and Networking          (204)474-7849        |
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| Paula Ehn  VE4MHZ/VE4HZ                    Room E3-628 EITC     |
| Unix System Administrator                  pehn AT cc.umanitoba DOT ca |
| Academic Computing and Networking          (204)474-7849        |
| University of Manitoba                     Fax: (204) 474-8534  |
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