Non Rewinding Device Path in AIX

Question

Hi,

I observed in my setup that after every backup the tapes are rewinded to start. It is causing backup performance very low. I am using Scalar i500 library. I configured it with jbconfig and did not bypass autoconfiguration. I was in the hope that it will automatically take non rewinding device path.

Since I am new to AIX environment I do not know which path to use.

Any suggestions.

ble1 · Accepted Answer

It is normal that if volume went from idle to done state then upon next 'contact' NW will verify label first and the move forward X file and record numbers to position on first next empty spot.  Since drive operations as such are slow there is an impact on speed, but this is nothing new and this limitation comes from HW design itself.

ble1 · Answer

Are you using /dev/rmt/X.1 devices?  Because you should use those... (you can also use X.5 if you want which is same as X.1 with lower density).

HCLBACKUP · Answer

Hi Crveline, I am using /dev/rmtX.1 name.

ble1 · Answer

Then you are using correct device nomenclature.

HCLBACKUP · Answer

Then what else can make it rewind after each backup.

ble1 · Answer

Why do you think it is rewinded?  Your device may go idle and writing done state... if new operation is requested then NW will by default check label first despite volume being checked first time it was loaded.  In some cases this may look as rewinding.  Can you paste the log from the server so we can see this more clearly?

HCLBACKUP · Answer

I will post soon.

HCLBACKUP · Answer

Hi Crveline,

I checked the daemon but there is no such entry which is related to tape movement. As the tape was already mounted to the drive. When backup started in the monitoring window I am able to see the message of rewinding the tape and then moving forward x number files.

After every backup the number of file count gets increase. It takes around 10 mins to start the backup. However there is only 55 GB of data in the tape currently. I am wondering that if the data on tape will be in TB then how much time it will take to actuallyy start the backup.

Regards,

HCLBACKUP

NetWorker

Non Rewinding Device Path in AIX

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