StorageWorks Dat 72 problems

[Craig_79]

Compression is not working. Drive says compression capable = True but compression enabled = false. Problem is I can't change it, it's greyed out. Using Veritas software. Running MS SBS2003 OS. Using HP Dat 72 tapes. Why am I having this problem?

[Satish M.S.]

Craig:
One way to enable hardware compression is to run a test called the 'Compression Test' using the Library and Tape Tools Diagnostic Software that can be downloaded from
www.hp.com/support/tapetools

When you run the compression test, you will see a message that basically tells you that 'hardware compression may be disabled, would you like to enable it?' Choose 'Yes'. This is one way to do it, although it doesn't really guarantee it.

Have you also tried to stop all the backup services and restart them? Many a time this resolves the issue as well.

[Craig_79]

I ran Ltt and bytes written & bytes read are the same, meaning 1:1. So I upgraded the Dat72 firmware from v303 to v312. Reran Ltt and now looks like compression is 2.2:1. thought I would be good to go, but unfortunately A full backup revealed 1:1, and can't do full backup still.

[Marino Meloni_1]

Standard settings on DDS tape set the compression on but allow SW overwriting the setting.
this mean that if you boot your server, after a power down, the compression is enable by default. if another backup application is then started, this application can overvrite the default setting, and set compression off.
This can explain why some time you see compression enable and some time disabled.

[Craig_79]

Something very wrong with Veritas, it still says in various places the firmware is still v303. I think tomorrow I will reinstall Veritas. Shall I use HP drivers or Veritas drivers, is there any consequences/advantages to either?

[Craig_79]

Thanks Marino, Then I am correct in thinking the software (Backup Exec) is the main suspect here? I will reinstall. Which drivers should would you use, Veritas or HP drivers. I always like to go with Manufacture drivers, but unsure in this case.

[Marino Meloni_1]

I usualy use HP drivers. in case of problem, I try with the Backup application drivers.
Be sure to have a Backupexec version supporting the DAT72.

marino

[Craig_79]

It does, just checked.

[Craig_79]

No go. I un / reinstalled Veritas without their drivers. Backed up .986:1. That is not compressed, it is larger. Used hardware only compression selector in Veritas. Will try hardware then software compression tonite. What if veritas compression is off and let hardware do things itself? Ever tried that?

[Satish M.S.]

Craig:
I was on the Veritas Support Website and found a few documents of interest. A few questions to ask you though:
1. What version of Veritas are you running
2. What do you have running for an OS?

Please click on the following link(s):
http://seer.support.veritas.com/docs/258821.htm
Document #: 258821, http://support.veritas.com/docs/258821

This document basically outlines as to how to go about enabling compression whether be it software or hardware. The document outlines as to how to enable the software compression. On the contrary we will have to make sure hardware compression is enable for optimum performance/results. So, kindly try the following:-
1. In the Backup Job Properties, click General under Settings .

2.Select Hardware (if available, otherwise software) from the Compression type drop-down list.

3. Continue with configuring the rest of the backup job, and then click Run Now.

Restart Veritas BackupExec for the changes to take effect.

[Craig_79]

Here is the latest, it is getting weird. I have a question at the end.
Backed up the same folder with 2gb of data the following ways using Veritas v9.1:

Compress set to None 1.062:1
Compress set to Software 1.045:1
Compress set to HW else none 1.104:1
Compress set to HW else SW 1.077:1

I then tried Windows Backup, but due to other circumstances it failed, so I went back to Veritas. Windows BU had renamed the tape to Seagate with today date. The tape was named named 4MMxxxxxxx. Weird. I left it like that and started a full system backup. I checked the media and it said compression 1:1. So I let it run while I checked other settings in various places, found nothing wrong. I stopped the tape after 15 minutes because the tape wasn't going to hold everything anyway. After it stopped it showed media compression at 1.775:1 !! It may be working now, the server won't do another full backup until tonite.

Where can I find documentation of compression ratios of different file types? This server has many large powerpoint, avi, mjpg, gpraphics file types. Some powerpoint presentations are over 300MB. A very large portion of the files contain some some sort of graphics in them.

[Craig_79]

Satish:

Those links are for backing up to a folder not to tape. The compression setting are located in same place for either method.

I do find it intersting at the end when you said "Restart Veritas BackupExec for the changes to take effect". Do you mean close & reopen BEXEC, or the services themselves?

Not everytime did I close & reopen. Never did I restart any services. Hhhhmmmmmmm. I wonder........

[Marino Meloni_1]

Looks like you are getting some kind of compression anyway, the ratio you report is not 1:1 but something different, this mean that compression is enable.
Now, the cause of the poor compression is due probably to your data.

Nowaday all the OS use to optimize filesystem, and same for the various application that create files, media files are already highly compressed and cannot be more compressed, and if you try to compress them, you will have more overhead than benefit, and you will go under 1:1

I would suggest you a system to identify if the cause are the data: start LTT, and go in the system performance tab, then run the prerestore data test, selecting a set of data with 2:1 compression. This will create you a amount of data with a well known comprimable ratio. THen try to backup these data, and check the result, should be 2:1.

[Satish M.S.]

Hello Craig:
This is indeed getting interesting. Stop all the backup services and restart them. Do let me know if it is of any help.
Thanks

Satish

[Joshua Scott]

Craig,

All of the standard media formats are already highly compressed as a part of the MPEG/JPEG/AVI format. This is why you may see an increase in size on those type files. Even in lossless formats like MPEG-1 and WAV, the files are compressed using a ZIP type algorithm when the file is created, so trying to compress it again only adds overhead to the file.

Josh

[Craig_79]

Marino: I miss read your suggestion earlier and installed HP drivers only. That is what I was using before reinstall also. I will try the LTT suggestion. May need to try Veritas drivers.

Satish: I will also remember to restart the services after any new config change.

Joshua: I crunched some numbers from 1 partition: The average file size comes to 1.2MB. I can believe that. (23+ GB divide by 19396 files)

The last data only backup had a compression result of 0.935:1 . You have all helped very much with my problem. All the latest suggestions are going to take time.

Can anybody spell "Archive" !! ?

If they don't want to archive (may not be convenient) and if everything turns out to be a result of the data type and its compression capabilities, what type of backup hardware would you recommend? I have only worked with DDS tapes/HW before, so what is the next step up?

[Melissa Schaefer]

Hey hey wanted to let you know I am suffering from this same issue. I have a ML530 with a fixed interal Dat72 and my compression is showing 1:1. With veritis or HP drivers.. Compression = False is grayed out. We have figured out that our issue does lie with Veritas. HP is sending me a new drive (it's on backorder) Because they couldn't figure it out.. hope that makes ya feel better :-)

I had this same issue on a couple DL380s with a hotswap Dat72 and the one with Veritas was not compressing and the one without veritas was compressing fine. So it is something to do with Veritas. We are running Veritas 10 and 10d.
To fix the 1 server we did several things but not sure what fixed it. I stopped veritas services stopped the tape backup service opened the tape tools and did a compression test. It never asked me to enable like some guy mentioned. Well we closed that and opened veritas enabled the service and logged in and right clicked on the tape drive and made sure compression was on. We then went into tools and options and Backup Compression type Hardware if avalible otherwise software. We then made sure the job was set the same. We then checked and no luck.. we then swapped the hot plug drives from the server without veritas to this one and well it was amazing and it found the new drive and walah the compression was enabled. It was the weirdest thing but hey it worked. We even rebooted and it stayed. So we deleted the old tape drive in veritas and it is still working.

[Craig_79]

Very interesting, Melissa. Wish I has a spare to swap. May be calling HP soon too.