Tape Duplication - Is Compression Enabled By Default
I had a backup job that actually spanned three tapes - it has at least 3 TB or more data that it is running a full NDMP backup on. This is from a NetApp filer, via NDMP, and to Ultrium 5 tapes. The original backup uses no compression. The backup job took 27 hrs. THis is using one Master/Media server and one Dell Powervault TL4000 dual head library. The NBU server is running NBU version 7.5.0.5.
This is the first time I have ever run a duplication job. I used a Catalog based duplication. I was prepared for the job to basically take something less than the 27 hours the original backup took. It ended up being 6 hours and change. I also expected it to need three tapes, it used one. I am concerned that something is rotten in Denmark, this is to good to be true . Does this make sense? Is compression automatically enabled on the duplication job? How did it fit on 1 tape without c ompression?
Let me know if you have any insight into theis. I am scratching my head and really wondering what is on that one tape. I will obviously run some kind of inventory report on it.
Last question - is there any way to tie out the Job ID you get in the Activity Monitor to the Backup ID you get in the reports? Is there a report that lists both? None of the canned reports that you get from the Activity screen have both values. I ran a couple of reports and exported them into Excel and did some Excel magic to get the desired result, but there must be a report.
Thanks in adhvance. I appreicate any help you provide!
Joe
The drives use hardware compression by default, for example, if on Solaris the path was /dev/rmt/0cbn to the drive, the 'c' bit of 'cbn' means compress.
So the tape driver / tape drive hardware handles compression.
I would run a verify on each copy, make sure they check out.
At the moment, I can't explain the difference, but have seen similar on a multiple in-line copy where one copy used x tapes and the other used x+1 tapes, exactly the same data being sent to each drive at 'almost' exactly the same time.
Both copies were readable, issue was a fault with the tape drive, one of them wasn't compressing.