| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 8648.1 | OP:HIGH mrd_show() incorrect on RW500 | NABETH::alan | Dr. File System's Home for Wayward Inodes. | Thu Jan 30 1997 13:27 | 30 |
| 0. Please put such wildly separate questions in different notes.
1. Restore from the backup you made before you did the upgrade. You
(the customer) DID make a backup before the upgrade DIDN'T they?
2. Not with those utilities. If the customer wants backup with media
management, they should buy NSR. I'm also curious how they're
using the optical drive. Some drives can pretend to be SCSI Direct
Access devices (disks) instead of Optical. I don't know which of
drives support this feature. For those that can't you need the CLC
Optical driver, which is only licensed with the products that use it.
Even if those utilties supported sequential loaders, I don't know
if the medium changer on that drive is sequential or purely random.
3. The 40 GB capacity for the TZ88 assumes 2:1 compression of the
data. Some data compresses better, some data worse. The algorithm
used by the TZ88 may be one that the data can actually grow when
handed some types of data. A good example of this type of data
is that which has already been compressed.
Compression on top of Compression is usually a good way to make
the resulting data get larger. This is probably the problem.
If the customer wants to use software compression, they need
to use one of the lower density special tape files that won't
use drive compression. Or don't do software compression and
let the drive do it.
This still may not get the full 40 GB capacity, but it should
help. Remember, the compressability of data, depends on the
data.
|
| 8648.2 | | DECWET::RWALKER | Roger Walker - Media Changers | Thu Jan 30 1997 13:30 | 14 |
|
I'll skip the downgrade question.
If you want to automate backups to an optical drive you need a product
like NetWorker that will combine both the backup processing and the
device management.
If you select software compression on a backup such as the -C switch
to vdump you will only get the native capacity of the tape ~20GB.
Unless you are going over a network link it is better to let the
hardware do the compression (less CPU load). Using the /dev/nrmt*h
device selects hardware compression, you do not need any switches on
the backup command. Compression can vary from 1:.9 to 20:1 depending
on the data.
|
| 8648.3 | thanks for the answers | METMV3::COX | | Thu Jan 30 1997 13:59 | 14 |
| Thanks for the answers...
reply .1 This was a fresh V4.0 install. The issue is with a version of
one of thier Oracle apps. They need to go to V3.2D, upgraded to Oracle
stuff then upgrade to V4.0 . Looks like a fresh V3.2x install coming
up.
Next time I will enter separate notes, Sorry :-(
As for the optical drive, they have Networker, we haven't tried it due
to some other issues with the optical drive. Time to give it a shot.
I thought compressing compressed data sometimes made it grow, just
looking for someone to confirm.
|
| 8648.4 | Use hardware compression | DECWET::RWALKER | Roger Walker - Media Changers | Tue Feb 04 1997 13:04 | 11 |
| Generally we recomend using the device compression even
if the data is already compressed. For an application
like NetWorker there are still extra label and index blocks
added to the data stream that do compress. Since it is
harder to change the hardware compression (must delete
and redefine the device) the /dev/nrmt*h device should
always be used.
The customer can turn on and off the client compression
until they find the best mix for their use that balances
CPU usage and network load.
|