Migrate COS data to new server

[booman55]

We are in the process of assisting a customer with a DC move of legacy server and they use IBM COS for backend storage. The new server host has disk pool and tape available. The source host has lots of NAS file backups with millions of files stored on COS.

We've been doing node replication as means to migrate the data. I've tried using 4 streams and replicating direct to the 4 tape drives. I've tried putting nodes in nodegroup and replicating to disk pool with 40 or 50 sessions. Neither has been great with performance. All SP instances are running v8.1.13.

Any tips on performance settings or best practices when trying to migrate millions of files on COS to new server??

 

[marclant]

When dealing with millions of small files, there's a lot of database transactions. Make sure the database is on the fastest disk possible and use 12 database directories mounted to 12 filesystems, and each filesystem representing a LUN on the storage.

You'll have to backup the DB and restore it if you have a smaller number of database directories today because if you just add directories, it will take a while before the DB is balanced, so you want get the benefit right away.

The reason for several directories is that DB2 will increase the amount of parallelism it does when presented with more filesystems.

Replicating to disk is also the best approach and using large number of sessions like you are doing will be faster than directly to tape. You can migrate to tape after or even during.

It's possible the reads from COS are slow as well, but I don't have any experience with that.

 

[booman55]

DB is spread across and provisioned appropriately. I'm thinking it's reads from COS, but was wondering if anyone had experience with migrating COS data.