Posted on 2004-04-08
Last Modified: 2013-12-01
I am running veritas 8.60 rev 3878 on a file server with a c:\ drive with 2.24GB and a d:\ drive with 53.6gb. This is a total of 55.84 gigs of data that is fully backed up every night. The last known good backup I have had was around 43.5GB. It has grown as usuall to the 55.84gb of total data. It is around 46.5GB that it stops trying to backup at and gives me a error telling me to remove the media from the drive and then prompts me to insert media into the drive. If I keep trying to use the same media tape it will do this endless loop of asking me to remove and insert media. If I insert new media then It continues the backup on a second tape. After it finishes the backup on the second tape then it will want me to insert the 1st tape for verification, and I am assuming the second tape but I have not gotten that far yet.

For the compression setting I have "hardware if available (otherwise none)" set for this nightly backup job. The taped drive That I am using specifies 40GB native and 80GB compressed.

I think I am exceeding the amount of data that my backup can handle.

This drive is a DLTVS80 using DLTtape IV tapes 40GB/80GB.

I have downloaded dells powervualt DLTVS80 tools and tested the drive out. It reads and writes to tape media just fine. I am finding no errors with this drive.

I tried updating veritas to the latest 8.60 revision.

I have tried cleaning the tape drive 2 different times just because.

I have hardware compression enabled in veritas on this drive. Under devices, DLT drive, properties on the configuration tab I have hardware compression enabled with the following settings
block size=32k
buffer size=32k
buffer count=10
high water cound=0

What am I doing wrong here shouldn't this tape be able to handle 80gigs of data as long as its getting compressed. I thought this is where the 40GB native and 80GB compressed came into play. I should be able to back up 80GB of data as long as its getting compressed to the tape drive right? I have tried to find if this powervualt DLTVS80 drive supports hardware compresion but I have not been able to verify it yet. Maybe I have the wrong driver installed, but I doubt it.

Question by:illtbagu
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LVL 32

Expert Comment

ID: 10784911
Hi illtbagu,

> he last known good backup I have had was around 43.5GB. It has grown as usuall
> to the 55.84gb of total data.
This can happen depending on the kind of data that has to be backed up. Sorry to say this, but you will have to look for either bigger tapes, or for a different backup scheme (like a full backup in the weekends using two tapes, and a differential backup each day of the week)



Author Comment

ID: 10784931
Here is the specs for the DLTVS80 drive it supports hardware compression.
LVL 32

Expert Comment

ID: 10784949
I know, but a 40/80 tape can hold over 200GB of plain text documents, but only 40GB when all files are JPG/MP3. It all depends on the filemix. With the filemix you have you won't be able to get more than that on a tape.
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Author Comment

ID: 10785564
So how in the world do you try and pick the type of drive that you will need to do an entire backup of a server. For example, someone hands you a computer that has 60 gigs of files on it and they say put a tape backup drive in this server that can do a full backup of the entire data on the hard drive/s onto 1 tape. In this case with a 40/80 drive you will need compression to get the job done. And since you don't know how much the data on the hard drives can compress down to you are up $#!~ creek with out a paddle. In other words take your best guess. You can't  know for sure unless you try it out and see if it will backup all of your data or not. This is crazy.

What do you do look at the type of files that is on the hard drive and then make a decision on your type of backup drive. There is no way to tell for sure. Most file servers have many different types of files they may be serveing, maybe even hundreds of different types of files like we have.

There has got to be a way to find out when your tape backup will stop doing a full backup because it ran out of tape space. Where was the red flag for me that was supose to let me know that I was very close to exceeding my tape backup limits. This is freaking crazy.

Maybe NAS is the way to go but I sure don't want to get into that disscussion right now.

Thanks for your help LucF
(Please don't take offense but I cant help myself. Is LucF short for Lucifer as in the devel)
LVL 32

Accepted Solution

LucF earned 400 total points
ID: 10785692
>>So how in the world do you try and pick the type of drive that you will need to do an entire backup of a server.
I usually pick a compression rate of 1.4:1 to estimate the amount of data that should go on a tape in an average file mix. In your case, you are not very lucky and have a lot of badly compressable files on your server :( I've personally never seen anyone getting 2.0:1 compression as advertized with by the tape manufactors.

>>Please don't take offense but I cant help myself. Is LucF short for Lucifer as in the devel
No offence taken, I find this question kind of funny actually.
Nope, it's just my first name and the first letter of my last name. But you just made my day by asking this.


Luc Franken

Author Comment

ID: 10785817
I always like to try and figure out user names on sites. Mine is kind of obvious and has been carried over from the good old days back in the mid to late 90's when I was laying the mac down on all of the AOL chicks. Its time for me to change this. Just old habbits I guess.

Your right, my compression is bad. 1.1:1 I think, maybe even less like 1.08:1. That is really bad.

Im just trying to figure out how the heck I can tell after doing a full backup how much space is left on the tape. In other words how much of the tape is being used, 80% 90% or what. You can't, it seems there is no way of telling how much of a tape is being used and how much free space is left. This is crap.

Thanks again.
LVL 63

Assisted Solution

SysExpert earned 100 total points
ID: 10787394
You have a few choices.

1) Buy a bigger Drive.

2) Buy a tape Library or loader.

3) Use Full for weekends and Differential for daily. If not all the data changes, this could be a big space saver.

I hope this helps !

Author Comment

ID: 10787762
I will probly just buy a bigger drive if I can get it approved. I would still like to do Differential daily backups on Monday-Thursday and full backups on Friday.


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