Re: Clear or Delete Library

On 13-Jan-2016 11:01 -0700, Steve Pavlichek wrote:

Is there a performance difference between a CLRLIB and DLTLIB? I have
a customer who is refreshing over 10TB of data from PROD to DEV using
BRMS save/restore and is needing to get the process done quicker.

Mostly there should be no difference betwixt.

They are submitting CLRLIBs to batch and are running multiple jobs
concurrently. Would single threading these help at all?

If very few objects make up that 10TB, then possibly there could be benefit in single-threading the Dlt|Clr requests. If the length of time taken is mostly per a large number of objects, then probably not. If there is no obvious answer, then another option to consider is to temper\throttle-down the amount of concurrency; e.g. if there are many libraries, then perform the work against only a few concurrently, perhaps by limiting the job queue to allowing only three jobs to enter the subsystem.

Any other suggestions?

Concurrent DROP CASCADE of unrelated database file networks or concurrent effective reverse-creation-order DROP RESTRICT [or Delete File (DLTF)] of the database files with retry-after-delay per error on restrictions, issued preceding the Clr|Dlt requests might perform better overall wall-clock time; sequentially with actual reverse-creation-order instead of concurrent delete, probably could not compete performance-wise.

Presumably all the files in a library are journaled. If many are journaled to just one journal to which no other files outside that library [or set of libraries], then there may be benefit in ending journaling in one request [i.e. ENDJRNPF *ALL] to precede the DROP activity, rather than for each file to be processed in the manner individually when dropped.