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Media density

Vjeksa
Level 4

Hi,

I've LTO6 tapes in robot but approx only 740 GB can be written on them.

Drives and tapes are defined as hcart3.

Any suggestion why only this ammount of data are backed up in one tapes before NB asks for another?

1 ACCEPTED SOLUTION

Accepted Solutions

mph999
Level 6
Employee Accredited

LTO6 should hold about 2.5 TB (uncompressed) or around 5TB compressed.

Even if the data written is not compressable, you should still reach at least the native capacity (2.5TB).

NetBackup does not understand tape capacity, it has no idea how big a tape is, or when it becomes full.  The NetBackup densities (hcart/ hcart2 etc ) make no difference, there is no tehnical meaning behind them other than to be sure the density of the tape matches the drive.

When a tape becomes full, this is detected by the tape drive firmware.  This sets a 'full' flag in the tape driver (all of this is outside of NetBackup).  When NetBackup tries to write more blocks to the tape, the write is refuseed by the tape drive driver, and it is this that tells NBU the tape is full, and a new one is needed.

Therefore, the issue is either with the drive firmware, the tape driver or a hardware fault with the drive.

Unfortunately, there is no troubleshooting or fix available from NetBackup for this issue.

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1 REPLY 1

mph999
Level 6
Employee Accredited

LTO6 should hold about 2.5 TB (uncompressed) or around 5TB compressed.

Even if the data written is not compressable, you should still reach at least the native capacity (2.5TB).

NetBackup does not understand tape capacity, it has no idea how big a tape is, or when it becomes full.  The NetBackup densities (hcart/ hcart2 etc ) make no difference, there is no tehnical meaning behind them other than to be sure the density of the tape matches the drive.

When a tape becomes full, this is detected by the tape drive firmware.  This sets a 'full' flag in the tape driver (all of this is outside of NetBackup).  When NetBackup tries to write more blocks to the tape, the write is refuseed by the tape drive driver, and it is this that tells NBU the tape is full, and a new one is needed.

Therefore, the issue is either with the drive firmware, the tape driver or a hardware fault with the drive.

Unfortunately, there is no troubleshooting or fix available from NetBackup for this issue.