A tape block is 1,024 bytes of data. In the dump command, you can specify the number of tape blocks that are transferred in each write operation. This number is called the blocking factor.
If you use a storage system for both the backup and the restore, you do not need to specify a blocking factor. Network Appliance recommends that you use the default blocking factor of 63. On a storage system, you can specify a blocking factor from 4 through 64.
Note
Dump backups do not allow tape block sizes bigger than 64KB. An attempt to use block sizes of greater than 64KB will result in failed backups.
On a remote host that is not a storage system, you can use a blocking factor from 4 through 256, provided that the host supports the blocking factor that you choose.
Note
SunOS 4.x and earlier versions do not support a blocking factor greater than 63.
If you plan to restore to a system other than the system that did the backup, the restore system must support the blocking factor that you used for the backup. For example, if you use a blocking factor of 128, the system on which you restore that backup must support a blocking factor of 128. A blocking factor of 128 would mean that you could not restore the backup using a tape drive that is connected to a storage system.
To specify a blocking factor for a backup, complete the following step.
| 1 |
Include the b option in the dump command line. Note |
The following command backs up the /vol/vol0 volume using a blocking factor of 32, so that 32 KB of data are transferred at a time:
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Part No. 210-01080_B0
File: dump21.htm
Last updated: 08-Dec-2005 13:23:37