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beatdown (TechnicalUser) (OP)
12 May 08 14:49
We're using Backup Exec 12, with a Dell PowerVault 122T. Tapes are VS80, 40GB/80GB.

I've been doing the backup uncompressed, but we're getting to the point that there's so much data being backed up, it takes more tapes than we have available, and the backups run all night and into the next morning.

My question, is what exactly are the pros & cons of doing compressed backups?

From what I understand, this will allow us to get close to 80GB of data on each tape, and will also increase the speed of the backups.

Anything else I need to know about or consider? How does this affect restores, etc....

Thanks for any advice you may have!
LawnBoy (MIS)
12 May 08 15:24
The only real con is that there is no guarantee of compression. You *might* get more data on that tape; different file types will compress at different ratios. Text files will compress down to almost nothing but a .zip or .jpg won't compress at all (because they're already compressed).

Having said that, I have one system with BE 10 running the same deck you have. I'm getting compression ratios of 2.25:1 (which is the highest ratio I've ever seen) allowing me to get about 90GB on that 40GB tape.

I have other systems where I'm not getting any compression at all.
 

"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 

wheelgunr (IS/IT--Management)
13 May 08 15:37
We use 12d for our CPS Exchange backups. The media server is attached to a PV122T, LTO1 (100/200). I get aps 1.5 - 1.7 to 1 compression. The thruput for the tape BU is apx 1245MB/Min, so a full BU to tape takes about 3 hours (250GB of data). We also use the time/date option for the backups, so the system isn't continuously backing up the same data, only that which has changed since the last Full or Diff.

If your 122T is like mine, with 8 slots, I partition the slots for 3 tapes for a full BU, and 1 slot for the Diff BUs. This gives me Sun - Fri backups. Once our system settles down (we just went to 12d CPS for Exchange), I could see dropping the 3 slot partition to 2, thereby giving me full tape BUs.

Hope this helps.
beatdown (TechnicalUser) (OP)
14 May 08 11:34
Thanks for the feedback.

So it sounds like if I switch to the LTO1 type tapes, my job rate will improve significantly. With the VS80 tapes, you only get about 10GB an hour.

With our VS80 tapes, it takes about 10 hours to backup/verify our 50GB Exchange database.
beatdown (TechnicalUser) (OP)
14 May 08 11:43
After looking into this more, I realized there are different models of the Dell PV 122T. So I can't just switch to LTO1 tapes, because my PV is made for VS80.

Looks like it's time to upgrade the LTO capable PV unit....

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