How much cache is too much?

[former_SQLA_member1694898]

I know - you can never have too much cache or is that cash? I always confuse the two.

My question relates to a 12 DB that is about 60GB in size. Right now we are starting it with 2GB (-c 2G). We are running on Solaris and the prstat command shows it using 29GB of memory. I am assuming this is due to it growing the cache as needed. My question pertains more to how much should we fire it up with when we start it? If we have 64GB available, does it make sense to start it with 45GB of cache? Would that help performance at all or is the way we are doing it about the same?

Right now we are in the process of paring down the DB (i.e. delete a bunch of records, unload, reload) and that process on this DB takes about 20 hours. This won't work for us as it is a mission critical DB and although theoretically possible using dbtran of logs etc to bring the new one up to date, it is just too long. I'm trying to figure out what will improve the speed of the delete, unload, reload. I'm using an SSD drive and doing the unload to another drive so that we are not thrashing on one drive all the time. We currently only have 32GB of RAM in the server and I want to up it to 64GB if it will help the process.

The impetus behind this process is that I am getting nervous about the overall size of the DB (60GB+) Is that even something to worry about? Performance is still more than acceptable and there is no slowdown at all, I am just thinking that backing out the stale data and paring down the size is good insurance and will help the backups etc. Am I just being paranoid or is there nothing to worry about with a DB this size with 12. I come from the Watcom days when the old "Assertion" message would have you staring at the screen screaming, "NOOOOOOOO NOOOOOOOO PLEASE GOD NOOOOOOOOOO" 🙂 🙂