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HP OpenVMS Systemsask the wizard |
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The Question is: Hello, I have tried to increase VCC_MAXSIZE on some systems. Occasionally, if I get carried away with the size, I get and VASFULL or INSVIRMEM (can't remember which one) error displayed on the console when rebooting from doing the AUTOGEN after putting the new size in MODPARAMS.DAT. The system then comes up with 0 bytes of VIOC cache enabled. I know that this error is given when the various different memory allocation SYSGEN parameters create a virtual address space too large. I have seen some extracts from Notes conferences indicating that AUTOGEN does not incorporate the VCC_MAXSIZE figure i n its calculations and therefore gets 'caught out' trying to adjust for a correct sizing. To recover from this error I have had to readjust my VCC_MAXSIZE down and AUTGOEN/REBOOT until I get some VIOC cache. My question is, is there not a formula for calculating the maximum size for the maximum VCC_MAXSIZE for a given set of other SYSGEN memory tuning parameters? If so, what is it and why doesn't AUTOGEN know about it and warn me that I won't get any VIOC cac he when I reboot? Best Regards Edwin Thornber The Answer is : VCC_MAXSIZE is simply added to the amount of system memory required, older versions of AUTOGEN did not account for this. Each 1GB of process address space set via VIRTUALPAGECNT requires 1MB of page table space for the process. Multiply this by the BALSETCNT to determine the number of page tables that must be kept in memory in parallel. The WSMAX setting indicates the number of pages in the working set, and each page requires 8 bytes per page for the working set list for each process. Add in the size of the paged and nonpaged memory pools, OpenVMS itself, and random other data structures such as the VIOC cache. All of this must fit into S0 and S1 space, which has a maximum size of 2GB. OpenVMS Alpha V7.0 and later improve this -- the page tables move into S2 space in V7.0, and the lock manager data structures move from pool into S2 space in V7.2, for instance.
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