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DAT24e-Lack of Compression

Lawrence Smith_1
Occasional Visitor

DAT24e-Lack of Compression

I am running a P4-1.6GHz system with Win XP Pro. I am using the built in backup software. I just completed a full system backup where I enabled hadrware compression but that wasn't reflected in the time to backup or the amount of media consumed. I have about 13GB of data on my system and it took just over a full tape to complete the backup, and over 3 hours. I am using an Adaptec 2940 controller. Does anyone think that it is the controller that is the issue?
4 REPLIES
Marino Meloni_1
Honored Contributor

Re: DAT24e-Lack of Compression

hi
perform some checks,
--is the scsi channel well terminated?
--is the cable ok?
--have you some scsi time out in the event log?
--check wit the software called PAT what is the performance of your system
--are all task stopped when you backup data?
--check for disk fragmentation

check here for drivers and PAT

http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?prodNum=C1556A&prodName=hp+surestore+dat24e+external&locale=en_US&taskId=8418&taskName=download+drivers+%26+software&prodTypeId=12169&prodSeriesId=42846&prodSeriesName=hp+surestore+dat24e+external

bye
marino
harry d brown jr
Honored Contributor

Re: DAT24e-Lack of Compression

Lawrence,

A 24gb DAT tape ONLY HOLDS 12GB of data. With compression, and that's if your data is compressable, you can sometimes get 24gb if it can be compressed at a 2:1 ratio, sometimes you can get more than 24gb of data compressed into 12gb, especially if that data is ascii plain text.

live free or die
harry
Live Free or Die
Lawrence Smith_1
Occasional Visitor

Re: DAT24e-Lack of Compression

Marino,
>> is the scsi channel well terminated?
The drive itself is external and terminated and it is the only SCSI device in the system.

>> is the cable ok?
I assume so, but have no way to test. What is "ok"?

>> have you some scsi time out in the event log?
No.

>> check wit the software called PAT what is the performance of your system
My system comes in at 13.88Mb/Sec vs. the 1MB/s Typical transfer Rate Disk to Tape for DDS3

>> are all task stopped when you backup data?
I'm not running in safe mode, but I am not running any other applications either.

>> check for disk fragmentation
According to WinXP Defragmenter Analysis report: "You do not need to defragment this volume": Total Fragmentation 3%; File Fragmentation 6%; Free Space Fragmentation 0%

>> check here for drivers and PAT
I did that earlier and found that he only way to update my card bios is to have Adaptec mail me a new BIOS (it is an old card) I tried to do it through thir online process, but it failed, I will contact them next week. Because the 2940 is an old card I am wondering if that is the issue.

*********************************

harry,

>> A 24gb DAT tape ONLY HOLDS 12GB of data
I wouldn't be surpirsed if I only end up with 17 or 15 or 14 or 13 GB, but when I saw that I backed up 13.6 GB of data and it took more than one tape I was surprised. It would seem that I am getting the native size and not much more.
harry d brown jr
Honored Contributor

Re: DAT24e-Lack of Compression

Lawrence,

If your data isn't compressable then there isn't much you can do other than use multiple tapes. But I agree with you that if it is compressable, and you have the compression option on, then there is some other reason for your issue.

live free or die
harry
Live Free or Die