Re: Virtual I/O Caching Alpha/Oracle

In article <NEWTNews.822594935.7964.Bob_at_bobmc.gtionline.com>, Bob McGuire <Bob_at_Alpha> writes:
> Greetings netters.
>
> Has anyone out in Netland attempted to change the
> VCC_MAXSIZE parameters on an Alpha from the default of
> 3200 to something greater? I'm trying to get the Alpha
> running as best as possible with Oracle.

On a general multi-user system we see a read hit rate of around 90% with a 50MB cache:     

              System Memory Resources on 26-JAN-1996 09:50:41.02

Physical Memory Usage (pages):     Total        Free      In Use    Modified
  Main Memory (512.00Mb)           65536       23467       37827        4242

Virtual I/O Cache
    Total Size (Kbytes)          50000    Read IO Count                5953058
    Free Kbytes                  12648    Read Hit Count               5355658
    Kbytes in Use                37352    Read Hit Rate                    89%
    Write IO Bypassing Cache      7268    Write IO Count                457392
    Files Retained                  91    Read IO Bypassing Cache       252048
     

>
> If so, what have you changed the value to, and if there
> were changes, how were they, good/bad/no change or simply
> not worth the effort.

On an system with 3.2 MB (default) I typically see a hit rate of under 50% if there's a lot of activity. So it is worth experimenting at least.

-- 
Alan Greig                           Tel: (01382) 308802
University of Abertay Dundee       Email: A.Greig_at_tay.ac.uk
   ** Never underestimate the power of human stupidity **