Datasheet
8mm Tape Drives
DLT Tape Drives
Slow Backup or Restore on Some Tape Drives
Some drives are sensitive to the delivery of data to the tape drive. Some applications take the blocksize and block the
data block into lar
g
er blocks for transfer to the tape drive. Some applications call this the blocksize, or the buffer size
or blocking factor. Whatever it is called you need to understand that this tape drives performance(data rate)is
greatly effected when the system sends small blocks of data to the tape drive.
Try setting the tape drive block size to a large blocking factor. You may also increase the block size to decrease the
amount of small blocks transferred to and from the tape drive.
You should test your application to see at what blocking factor and blocksize you get the fastest backup and restore
with your particular system, tape drive, and application combination.
The minimum recommended blocking is 32k. Some AIX commands already use 32k or larger blocks when writing,
some do not.
Increasing the blocking factor to 256k may speed up the backup or restore.
The following are a few of the AIX commands and blocking information:
backup <- will either use 32k or 51.2k as default depending if backup
by name or not. N/S customer change required.
tar <- default is 10k
tar needs the customer to use at minimum -N64
mksysb <- uses backup on AIX 4.1 N/S customer change required.
dd needs the customer to use at minimum bs=32k
cpio needs the customer to use at minimum -C64
Users should insure the blocksize they select is supported by the users application.
Placing a Service Call
Only after all this is done, and the problem persists, should the tape drive service call be placed. When placing a service call
have the following information available:
z The type of tape drive you are placing the service call on, 5GB 8mm, or 20GB 4mm, etc..
z The machine type, model, and serial number of the IBM machine where the tape drive is installed. If the tape drive is
externally mounted this will be the information from the external enclosure housing the tape drive.
z The t
y
pe of problem bein
g
reported.
Capacity Model Description Test Tape Part Number
2.3GB drive 7208-001 21F8577
5GB drive 7208-011 21F8577
7GB drive 7331-205 21F8577
20GB drive 7208-341
7331-305
Mammoth 59H2677
60GB 7208-345
7334-410
Mammoth 2 59H2677
Capacity Model Description Test Tape Part Number
35GB 7205-311
7337-305/306
DLT7000 59H3039
40GB 7205-440
7337-360
DLT8000 59H3039
160GB 7205-550 SDLT320 35L1120
Page 55 of 93Tape Help Package
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