Parallel Database Extensions (PDE) Message 11085 - 11085 - Analytics Database - Teradata Vantage

Message

FSG physical memory calculations: AvailablePages(%lu) = ((TotalPages(%lu) - (PagesPerVproc(%lu) x NumberOfVprocs(%d)) x CachePercent(%d%)) - TvsPages(%lu)) MinSlotsPerAmp(%d) > SlotsPerAmp(%lu) = AvailablePages(%lu) / NumberOfAmps(%d) / 256 4K Pages per 1 MiB Slot

Explanation

This message is issued when the FSG subsystem finds that there is not enough physical memory available on the node to run the database. This message shows the values used in that calculation. It is followed by a 11084 message, which forces a TPA restart attempt. The following values are used in this calculation: TotalPages: The number of pages of physical memory that the operating system has marked as available at the time PDE is first started. This value is obtained once when PDE is started, and remains unchanged until PDE is stopped. PagesPerVproc: The number of pages PDE reserves for the operating system to run a vproc. The FSG subsystem leaves this many pages per vproc alone and reserves the rest for its use, so increasing this value reduces the amount of physical memory that FSG will use. This applies to all types of vprocs, and there is no separate allowance for non-Teradata programs; any adjustments for those purposes needs to be factored in to the overall value. This value can be changed by setting the fsgpagespervproc variable in the startup.txt file. NumberOfVprocs: The total number of vprocs that could be assigned to this node when other node(s) in the clique are down. This is calculated by dividing the number of vprocs in the clique (defined in the VConfig GDO) by the minimum nodes per clique (defined in the Control GDO). CachePercentage: The percentage of the theoretically available physical memory that FSG will actually reserve for itself. The value computed by combining the above values is multiplied by this percentage to reduce the amount of memory FSG uses. Values of less than 100% leave more physical memory available for other purposes. This is kept in the Control GDO, and can be changed using the ctl utility. AvailablePages: The number of physical pages that the FSG subsystem will reserve for its own use. This memory is unavailable for any other purpose for as long as PDE is running. This is calculated from the above values, except that a minimum of 1K pages (4MB) will be used. TvsPages: The number of additional pages PDE reserves for TVS vprocs. NumberOfAmps: The total number of AMP vprocs that could be assigned to this node when other node(s) in the clique are down. This is calculated by dividing the number of AMP vprocs in the clique (defined in the VConfig GDO) by the minimum nodes per clique (defined in the Control GDO). SlotsPerAmp: The number of 1 MiB slots available per AMP, calculated by dividing the number of amps by the total available pages. MinSlotsPerAmp: The minimum number of 1 MiB slots per AMP that is needed in order for the PDE startup logic to accept the proposed configuration. This value is empirically determined based on the needs of a fully loaded, production size database. In some environments, a smaller number of slots can be successfully used. This value can be changed by setting the fsgminampslots variable in the startup.txt file. However, attempting to run a full load on a system with less than the default number of slots may result in database hangs, which can only be corrected by increasing the amount of FSG memory. Note: These calculations allow AvailablePages to be reduced by increasing PagesPerVproc, reducing CachePercentage, or both. CachePercentage is generally altered because it is easier to change, but it makes no difference how the desired AvailablePages value is achieved.

Generated By

DBS file segment management.

For Whom

System Support Representative.

Notes

None

Remedy

This message is for informational purposes only, to assist in resolving problems that result in 11084 errors, as described under the remedy for that event.