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April 13, 2018

Fine-Tune: Net config file care and feeding

I’m replacing my Model 10 array with a Model 20 on MPEXL_SYSTEM_VOLUME_SET, so it'll require a reinstall. What’s the best way to reinstate my network config files? Just restore NMCONFIG and NPCONFIG? I'm hoping I can use my old CSLT to re-add all my old non-Nike drives and mod the product IDs in Sysgen—or do I have to add them manually after using the factory SLT?

Gilles Schipper replies:

Do the following steps:
- using your CSLT to install onto LDEV 1
- modify your i/o to reflect new/changed config.
- reboot
- use volutil to add non-LDEV1 volumes appropriately
- restore directory or directories from backup
- preform system reload from full backup - using the keep, create, olddate, partdb,show=offline options in the restore command
- reboot again

No need for separate restores of specific files.

Making backups while network services are running

Advice from James Hofmeister

The most common problem with performing backups in the past was that network configuration files were held open for READ/WRITE when the network was up. 3000 sites found they had no backup copy of the network configuration file NMCONFIG.pub.sys when it was time to install (reload) from backup tapes. I tested this on 7.0 building a CSLT and storing @.pub.sys, @.mpexl.sys, @.net.sys, @.arpa.sys on the same tape, and verified all of the network files including the configuration files were backed up.

Another problem from older systems was NETCP.net.sys was found missing in action following a install (reload) — and after it was recovered and restored from another source, then another system reboot was required to initiate NETCP. NETCP is now included on SLTs. 

Will the network function normally while backups are in progress? The answer to this is Your Mileage Will Vary. The building of a CSLT and the STORE process consume significant CPU, memory and IO resources.

From a networking perspective, TCP/IP networks are not guaranteed to maintain network connections in the event of severe system performance degradation. An acceptable level of CPU and IO performance is required to support TCP's ability to acknowledge the packets it has received (if a packet is not acknowledged it will be retransmitted as per the remote hosts configuration).

Also, an acceptable level of system bus performance is required to support the network hardware DMA to system memory -- if busy during a DMA attempt, the frame is dropped (store from disk to tape or from disk to disk consumes significant system bus band width).

07:38 PM in Hidden Value | Permalink

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