Hello Roberto,
... But reducing the virtualaddresslimit to 1024, it already shows me 1gb of cache.
The price is the reduction of memory...
Yup, this JFS thing is all about balancing the hardware resources in a manner most beneficial to the way YOU use YOUR machine. So there really are no generalizations, other than perhaps some starting points?
With my particular hardware combo I'm able to run this large of a JFS cache with 'VIRTUALADDRESSLIMIT=2048' setup. I found that going lower than that will start causing problems with our current applications, as others have pointed out as well.
So the 'balance' thing here is probably more heavily skewed towards 'being able to run an app' as opposed to 'having a fast FS cache'.
...I've still set up my ArcaOS NAS like this, but I don't see any performance improvements in file transfer.
I'll have to do more tests...
I would NOT expect at all there to be file transfer performance improvements, other than I suppose the fact that the larger cache allows your target write operation to be cached.
...
[C:\]cachejfs
SyncTime: 32 seconds
MaxAge: 128 seconds
BufferIdle: 8 seconds
Cache Size: 1048576 kbytes
Min Free buffers: 8000 ( 32000 K)
Max Free buffers: 15000 ( 60000 K)
Lazy Write is enabled...
One last comment is re: SyncTime, MaxAge and BufferIdle. Be careful with these. I have my setups as large as they are because my machine is hooked up to a UPS fulltime. Therefore, the chance of power going out and the JFS cache NOT getting flushed out is very minimal. Still, a hard TRAP could still happen, so there is always some risk there.
Just for reference, here are my notes on this topic:
/LAZY:synctime,maxage,bufferidle
enables write cache with the following parameters:
- synctime : the interval at which the sync thread runs
default = 16
- maxage : is the longest time that a frequently modified file is kept in cache
default = synctime * 4
- bufferidle : is the time indicating a "recent" change. Changes newer than this
value are not written unless the last write was older than maxage.
default = MIN(1,synctime/8)