John wrote: >I wouldn't say that VSAM is standardized at 4K blocks.
>In general: >A Control Interval can be any size from 512 to 8192 >bytes in increments >of 512 bytes, and from 8 KB to 32 KB in increments of >2 KB. >The underlying physical record size is chosen by VSAM, >and depends on device geometry. The physical record >size is equal to or less than the CI size, and divides >into CI size with no remainder. For quite some time, VSAM has been using the media manager as its device driver. The standard block on disk is 4K and all I/O's are 4K, even though the CI may change in size. Unless you have something older than a 3380 or an very old MVS, a track dump would show that the actual blocks on disk are 4K. Also, if you looked at PDSE data sets and QSAM extended data sets, the blocksize on disk will be 4K! MVS has for some time been moving towards a fixed 4K block. The problem is the data in the field has to catch up. ===== Jim Sibley RHCT, Implementor of Linux on zSeries "Computer are useless.They can only give answers." Pablo Picasso __________________________________ Do you Yahoo!? Yahoo! Mail SpamGuard - Read only the mail you want. http://antispam.yahoo.com/tools
