I have spent some time over at Compaq and have been able to play in the lab with Netware on a SAN. I have backed up Netware using Arcserve (and other backup software) over a SAN and have found that I was able to max out the "feed speed" of the tape library, which reduced what I call the tape "shoe shine" effect. "Shoe shine" is what happens when the tape needs to be repositioned for writing as new data becomes available within the tape's buffers and the TOC is updated.
If you force feed the tapes with fast disks, this happens less frequently and backup speed just about match the theoretical throughput of the tape drives. For non-impact backup for production volumes, I have found using SAN-based "clones" is the best method for Netware. Just create a mirrorset on the StorageWorks array for the disks you want to back up.
Using CLIscript on the StorageWorks stuff, you can automate the process. (NOTE: this requires a license for Snapshot/Clone on the StorageWorks array!)
Here is a sample cliscript to create a mirrorset:
cli add mirr m7 disk10300 disk20300
cli init m7
cli add unit d6 m7
Once you have a mirrorset created, you can install your applications on it so the application is RAID protected. When creating a clone of your production volume, you may still want the production volume to be RAID protected so you should use three disk mirror sets. Use the method below to add a third drive to your mirrorset using CLIscript. Please note that these commands may have changed for the new EVA disk arrays. These commands should work with version 8.5S and above of the StorageWorks firmware for RA and EMA storage arrays.
This routine adds a third drive into a mirror to catch up so it can become a clone.
# this sets the mirrorset for three disks
cli set m7 nopolicy
cli set m7 member = 3 (this sets the membership of mirrorset m7 to three disks)
cli set m7 replace = disk30100 (this adds disk30100 to the mirrorset)
cli show m7 # wait for the third drive to normalize
waitnormal m7 30 3600
The text below is a sample CLIscript to actually break off the clone and create a new unit from the clone that can be mounted for backup on your SAN connected backup server.
# remove third member
cli reduce disk30100
# wait for the unit to normalize for 60 seconds and show status every 30 seconds
waitnormal m7 30 60
# must create a new container which is a single drive mirrorset
cli add mirr m1 disk30100
# add new unit (!!!USE NODESTROY TO SAVE THE DATA!!!)
cli init m1 nodestroycli add unit d6 m1
# unit created, now add SSP for the unit
cli set d6 disable=all enable=Backup1,Backup2 (enable the disk for access by the backup servers dual HBA's)
cli show m1
The exact same capability is available from the Hitachi and other storage vendors that have similar capability in hardware (there are some exceptions). Check with your vendor. Some of the vendors also let you have RAID protected clones instead of JBODs. If this is important to you, ask your vendor if they have that capability.
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This was first published in July 2002