MVSFORUMS.com

[Rao]

What is speed and recovery in VSAM?

[kolusu]

Rao,

Speed/recovery are optional parameters when defining cluster or the Alternate Index.

SPEED]RECOVERY:

specifies whether storage allocated to the data component is to be preformatted before records are inserted. SPEED]RECOVERY applies only to initial loading.

When you specify RECOVERY, your initial load takes longer because the control areas are written initially with end-of-file indicators and again with your data records. When you specify SPEED, your initial load is quicker.

SPEED
specifies that the data component's space is not preformatted. Its space might contain data records from a previous use of the space, or it might contain binary zeros (its contents are unpredictable).

If the initial load fails, you must load the data records again from the beginning, because VSAM is unable to determine where your last correctly written record is. (VSAM cannot find a valid end-of-file indicator when it searches your data records.)

RECOVERY
specifies that the data component's control areas are written with records that indicate end of file. When a data record is written (during the initial load) into a control interval, it is always followed by a record that identifies the record that has just been written as the last record in the cluster.

If the initial load fails, you can resume loading data records after the last correctly written data record, because an end-of-file indicator identifies it as the last record.

Hope this helps...

Cheers

Kolusu
_________________
Kolusu
www.linkedin.com/in/kolusu

[Rao]

Hi Kolosu,

Thanks for your fast response

Cheers,
Rao.P