[Info-vax] RMS indexed file caching (was Re: OT: Steve Wozniak)

[Keith Parris]

Neil Rieck wrote:
> Our databases are based upon RMS-ISAM rather
> than something SQL-based. This means that a majority of our databases
> are sitting in the XFC (extended file cache) of main memory because
> our processes only need 1 GB.

XFC caching is a good thing, but you should probably look into enabling 
RMS global buffers, as they can be even more effective.

Many of the former objections to using RMS global buffers have been 
removed. They used to be scanned sequentially for lookups, but 7.2 
introduced hashed lookups. They used to be limited in numbers by a 
16-bit signed count word, but as of 8.3 the count is a signed 32-bit 
longword. They used to be limited by P0 address space, but as of 8.3 can 
now be in 64-bit P2 space. And the RMS locking algorithm improved in 
7.2-1H1 such that lock rates are dramatically decreased when global 
buffers are enabled.

See 
http://www2.openvms.org/kparris/HPTF2008_Sizing_RMS_Global_Buffers.ppt 
for more info.

Keith