+1 That makes everything clear. Thank you very much, Peter. This explanation was exactly what I want to get...
Am 16.01.2015 um 07:33 schrieb Peter Hunkeler <[email protected]>: > hope someone can help. I try to understand how a SMF RDW works. Basically I > have no problems to understand ?the whole thing? as long as the record is not > ?spanned?. To make it clearer: For example a RDW (first 4 Bytes) of > ?33.14.01.00?. OK, x?3314? tells me that the record is 13.076 Bytes long, but > how to deal with the remaining part the ?0100?? The only thing I know is that > the record is spanned actually. Does this mean that the next 256 Bytes > ?after? the first 13.076 Bytes belong together or how is this calculated?! > > > > > RDWs are 4 bytes. The first two are always the lenght of the record. The > fourth byte is reserved and is always x'00'. The third byte, the one you're > talking about, is always x'00' unless the record format is VBS, .i.e. spanned > records. > > > With non spanned records, a logical record must always fit into a single > block. For spanned format, the logical records may be split into multiple > parts, each one being written to a separat block. So, there is a first part, > there are zero or more intermiediate parts, and there is a final part. The > rightmost 2 bits of the third byte in the RDW indicat just this: > x'01' -> first part, .i.e. a new spanned record starts here. > x'11' -> intermediate part. Note that there is no sequence number. The > sequence is given by the sequence of the blocks. > x'10' -> The final part, .i.e. the end of the spannded record. > > > Note that even with spanned format, non-spanned records are allowed besides > spanned records. I.e. there may be records that do fit in a block, and they > will have the third byte as x'00'. > > > -- > Peter Hunkeler > > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
