Copy Tape to tape copy

Hi Alvian,

To some extent that is true if disk has deduplication. Because not all the data is written and for tape we have to write all the data.

Also tape speed depends on the hardware, to understand the speeds on the tape library, you can ran drive validation.

Procedure

1. From the navigation pane, go to Storage >Tape.

   The Tape page appears.

2. Click the tape_storage for which the drive has to be validated.

   The tape_storage page appears.

3. Under the Drives section, for the associated drive that has to be validated, click the Actions button  and then click Validate.

   The Validate Drive dialog box is displayed.

4. In the MediaAgent box, select the MediaAgent that must be used to perform the validation.

5. In the Drive pool box, select the drive pool that must be used to perform the validation.

6. in the Volume block size(KB) box, select the media bock size that must be used by the validation operation to write data on the media.

7. In the Chunk size box, select the chunk size that must be used by the validation operation to create a block.

8. In the Amount to Write options, choose one of the following options to write data chunks:

   • Select the Write chunks to end of media option to specify that the validation operation must write chunks to the end of the volume.

   • Select the Write the specific number of chunks option to specify that the validation operation must write only the specified number of chunks.

9. Click OK.

ref: Validating a Drive (commvault.com)

Hi, I too would say that the tape to tape copy “function” is somewhat, ok, VERY inefficient. The drives in our case all validate at ~265MB/s both R/W, yet when the T2T job is running it shoeshines along at a pathetic range from 120MB/s to 70 which is clearly not optimal for the drive health nor the media (probably). So why is this? Does anyone know if there’s some ancient limitation in this where it can’t just run at full-track speed to copy the contents from one to another even of the same generation?

OR, is there a better way to do a duplicate tape copy that I’m not seeing in the BoL?

thanks!

Hello,

When you say tape to tape… are you doing an aux copy OR a media refresh?

Generally with tape, I recommend to use multiplexing / combine streams at a value of 5. Keep in mind, the more you increase the backup here, restores may take longer as the data is not continuous on the tape.

https://documentation.commvault.com/2024e/expert/data_multiplexing_overview.html

It’s exactly what I said - the tape to tape copy command when you right click an assigned tape. All I want to do is make a replica of an existing tape. It has been running for over 28 hours and still is only 58% done.

Hi downhill,

I do not think that a tape to tape copy would accomplish a replica copy for you. It moves the data from one to another, then erases your source.

https://documentation.commvault.com/v11/expert/move_contents_of_media_from_one_tape_to_another.html

The tape copy is what I intend - the original needs to be repartitioned, long story.

So are you saying the only way to expedite this sort of process is to muck around hand selecting jobs and doing an aux copy thereby needing to setup yet another SP? Man, what a hassle for a one time operation. I used to be able to duplicate tapes with our old product at as fast as the drives would run, no problem, no shoeshining, etc.