Re: normally take LONG time to backup an ntbackup file using ntbackup?


"David" <nospam@xxxxxxxxxx> wrote in message
news:eILKALpOHHA.2312@xxxxxxxxxxxxxxxxxxxxxxx
windows 2000 server backs up data from itself and other machines to
another
server over the network resulting in about a 24GB ntbackup .bkf file. This
bkf file is on a windows server 2003 machine which then backs it up using
ntbackup to a locally attached DLT 8000 tape drive. The first backup, the
one over the network to the 2k3 server, takes a little over 3 hours. Then
the backup from that 2k3 server to the tape drive takes about 12 hours! Is
that normal?

The backup file is 24 GB. The tape drive is a DLT 8000 which has a
compressed 80GB capacity and a transfer rate of 12MB/s. Thats 96mbps
(12*8)
which is very close to the 100mbps network. So if I'm thinking about this
correctly the 'over the network' transfer rate and the 'tape drive'
transfer rate should be about the same. So I assumed the backup jobs
should
be about the same... in fact I assumed the backup to tape would even be a
little faster since the first backup did the task of compressing all the
raw
data into the one .bkf file.

what could be causing this difference in time? Is this normal? am I just
missing where the bottleneck actually is on the second backup job... maybe
the SCSI bus itself? maybe ntbackup choking on trying to compress the
already compressed bkf file?



I suspect your tape drive can do about 12 MBits/s (rather than 12
MBytes/s), which is about 1 MByte/s after allowing for control bits
etc. A 24 GByte file would take some 24,000 seconds to back up,
which is about 7 hours, which is in the same ball park as the 12 hours
you observe.

Your best bet is to carefully read the manual and the specs that came
with the tape drive. Note that your times will double if the verify
switch is on.


.

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