Author: Abid Hasan
Posted: Thu Oct 06, 2016 9:51 pm (GMT 5.5)
Thank you Robert, that did put things in prespective.
Though, the VSAM Demystified does say the below; which in a way tends to contradict the numbers which are calculated using the formula from 'Using Data Sets', as was the case you'd shared (and I'm not sure why Demystified says so, wasting space![icon_neutral.gif]()
). I'd think that for an all random read dataset - in a CICS environment (or batch for that matter), this might not be a best-fit, MIGHT even increase the supervisor calls when the CISIZE is increased, though I'd have to test it to support the claims, as I'm not knowledgeable enough in this.
Can you please also shed some light on the high value of Cylinders for primary, and not a rather balanced out value for both prim/secondary.
_________________
Thanks.
Posted: Thu Oct 06, 2016 9:51 pm (GMT 5.5)
Thank you Robert, that did put things in prespective.
Though, the VSAM Demystified does say the below; which in a way tends to contradict the numbers which are calculated using the formula from 'Using Data Sets', as was the case you'd shared (and I'm not sure why Demystified says so, wasting space
). I'd think that for an all random read dataset - in a CICS environment (or batch for that matter), this might not be a best-fit, MIGHT even increase the supervisor calls when the CISIZE is increased, though I'd have to test it to support the claims, as I'm not knowledgeable enough in this.| Quote: |
| ....For the data component, defining 4-KB CI size provides a compromise between minimizing data transfer time and reducing the occurrence of spanned records. In the index component, each sequence set CI maps one CA data component. Each record maps one CI in the CA data component. If the index CI size is too small, there is no room for records to map all CIs. This limitation makes part of the CA unusable, wasting space. For the index component, use a minimum Index CI size of 3584 if you are using a 4-KB data component CISIZE. ... |
Can you please also shed some light on the high value of Cylinders for primary, and not a rather balanced out value for both prim/secondary.
_________________
Thanks.