How many records can be fit into a particular dataset

ganga79 · New User Joined: 16 Nov 2005 Posts: 23

Homwmany records can be fit into a particular dataset which has info like this Record format . . . : FB
Record length . . . : 80
Block size . . . . : 27920
1st extent blocks . : 2
Secondary blocks . : 1
Thanks in advance

mmwife · Super Moderator Joined: 30 May 2003 Posts: 1592

I calc 5933 recs total max:

1 blk = 27920/80 bytes = 349 recs

1st ext = 2 blks = 349 recs * 2 = 698 recs
2ndary ext = 1 blk = 349 recs * 15 2ndary exts = 5235 recs
Total alloc = 1st ext + 15 2ndary = 698 + 5235 recs = 5933 recs total max depending on space available on the volume.

DavidatK · Posted: Fri Apr 28, 2006 8:31 am

I have always been told the same as you Frank, 1 primary and up to 15 secondary extents, depending upon availability of space.

However, when I tested it at my site, I allocated 50 blocks for a total of 17450 records. At extent 10, the system started to increase the extent size for each additional extent. There must be an available site controlled algorithm for this!

Dave

Bharanidharan · Posted: Fri Apr 28, 2006 9:21 am

Dave,
Do you have any space controller/supervisor installed in your system? Two years earlier, we were having serious space issues due to the huge volume of records added in the files and we were getting frequent space abends because of the py and sy extents having been exceeded. Owing to that, my mainframe admins have installed something called "SPACE-X" around 2 years earlier (not sure who supports it). This would do the same thing you described. So I guess system does not automatically increase the extents.

DavidatK · Posted: Fri Apr 28, 2006 9:52 am

Bharani,

I do believe you are correct; we have a package that was installed several years ago to help with space abends. It must have it's hooks in supplied 'exits' or replaced some of the system allocation routines.

I was just surprised at the result. I was fully expecting the number of records Frank came up with, I try to allocate the max records within 3 extents, so unless I?ve grossly miscalculated the number of records output I rarely see space abends.

Dave,