Cachecard and 128MB DIMM

[crestfallen]

Hi All,

Just a quick question please.

When using a 128MB DIMM with a cachecard, does the Tivo cache the important parts of the database or does it simply cache anything which it can, i.e. a random chunk into memory?

What are the gains from using only 128MB?

I only ask as today i had a move around and decided to cannibalise an old PC.

Thanks,
Lee.

[Mike B]

Good question. I'm only using 256MB in my cachecard - so I'm guessing only half the database is being cached. It'd be nice to know which 'half' :)

[stark]

I've got two cachecards. One with 256MB and one with 128MB.

The answer is the half of the database that was most recently accessed. When a request comes in, it replaces the oldest chunk that hasn't been accessed.

128MB is a lot better than nothing, just not as good as 256MB.

[blindlemon]

If you switch on diagnostics from the cachecard drivers you will see that a 128mb DIMM gives around 80% 'hits' on the cache - so at worst you are only likely to be missing around 20% of database reads.

My tests show that a 256mb DIMM give around 95% and a 512mb DIMM around 99.99% so although there are benefits in fitting a larger DIMM, they're not in direct proportion to the size of the memory.