JamPack by Metalogic
JamPack increases the effective size of a pack, by reducing the impact of checker boarding, and it can eliminate many of the throughput problems associated with “SECTORS REQUIRED” hangs on Unisys MCP systems.
JamPack requires no software patches, and has been tested on a wide variety of systems and different Unisys MCP levels. It has been run on a system with 110 packs on-line and on a halt-load family with nine members.
Metalogic’s SUPERVISOR and FLEX products can be used to further improve automated operation, and pack utilisation.
Why do you need it?
The Unisys MCP allocates space on packs in variable sized areas and as the files occupying these areas on a disk are being created, expanded or removed, the numbers and sizes of the available areas on the disk will change considerably over time. This leads to an effect known as “checker boarding”, the effect of which is very visible on most systems when programs hang with “SECTORS REQUIRED” messages, even though there is much more available space than is needed.
The problem is that the available space will usually become distributed in small chunks scattered over the entire disk, especially if there are large numbers of small, volatile files on the family. If nothing is done to alleviate checker boarding, then 17% of a pack must be kept unused to avoid a ‘SECTORS REQUIRED’ hang.
Supervisor is owned by Metalogic S.à r.l., Luxembourg.