topic Re: Compression issue in StoreEver Tape Storage

Compression issue

stiaga — Wed, 28 Jul 2010 10:52:04 GMT

Hi,
I have a issue with the compression of a HP Ultrium 232 LTO1: I use the /hc:on option in ntbackup but if I backup data over 105 Gbytes the ntbackup requires me another tape, so the compression doesn't work.

Firmware and drivers of device are the last, windows is up to date (Windows 2003 Small Business Server).

I I test the compression tape with HP L&TT the result is ok. Furthermore HP L&TT utility reports me that the compression is enabled (i see it also in windows device manager). The files that I want backup are mostly word files so they should be compressed easily.

Can you help me?

Thanks a lot.
Regards.

Re: Compression issue

RayB — Wed, 28 Jul 2010 12:59:21 GMT

This may help

When you use NTBackup.exe to back up your data to a tape drive, hardware compression is turned off even when you turn on the hardware compression mode. This problem occurs even if the tape drive supports the hardware compression mode

http://support.microsoft.com/kb/827475

Re: Compression issue

drk14 — Wed, 28 Jul 2010 18:01:28 GMT

Actually, the Microsoft KB article says that NTBackup does allow hardware compression during write operations, but that after completion of the backup (in NTBackup), hardware compression is disabled. Only third-part backup software attempting to use compression after it has been disabled by NTBackup is affected.

Moreover, I can confirm that enabling hardware compression in NTBackup does work. When enabling compression, the write speed is doubled, but the restore speed is halved.

For more information, please look at my recent thread:

Slow restore speed from Ultrium 920 External SAS

Re: Compression issue

stiaga — Wed, 28 Jul 2010 20:21:44 GMT

Hi,

I have just read this microsoft KB but I have already this patch because it is included in the service pack 2.

How can I resolve?