Estimating the space and the number of versions of the RXX
Article ID: 270651
Updated On:
Products
Issue/Introduction
How can I calculate the size of the RXX needed to save at least the information to rebuild a full day?
We have 255 versions of the RXX GDG with 1440 track each one , but as I will enlarge LXX, I have to increase the allocation of RXX and then 255 RXX GDG version will be a lot.
Environment
Release : 15.1
Resolution
Recommendation would be to size the RXX to be the same size as the LXX in case if a spill is delayed (one of many ways that can occur). You can add the ,rels to the allocation side of the jcl. If some reason the lxx goes to 100 percent and almost all is spillable the RXX can consume it without error. if you pre allocate a rxx file too small there might be a chance you will get x37 abend (space full). Or another method would be the primary allocation of the RXX can be smaller than the LXX is consuming but with the secondary you can grow the RX to the right size of the LXX if you need to consume 100%
For GDGS, we usually recommend the need as many GDGs that would represent the time of average backup cycles times two. So as an example, if backups performed every weekend, you would need enough GDGs to cover two weekend cycles -- so at least 15 days of GDGs. That's if the LXX is spilled to the RXX every 4 hours -- that's 6 a day times 15 days = 90 GDGs
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