That's exactly what I was after. Thanks for the detailed explanation!
Scott On 02/07/2013 12:53 PM, "Leif Hedstrom" <[email protected]> wrote: > On 7/1/13 3:41 PM, Scott Harris wrote: > >> >> Hi, >> >> We are currently looking at upgrading to ats from some bluecoat web >> caches and trying to find out if ats has a hard limit on max number of >> stored objects? (Not single object size, I know there is a setting to >> control that) >> >> I ask this because our bluecoats have a hard limit of 32 million objects. >> >> >> > It's a calculation based on the size of your disk cache, and the setting > proxy.config.cache.min_**average_object_size from records.config. > Basically, you get one "directory entry" in memory for every 8KB of disk > cache. You always consume at least one directory entry per cache object, > but it can be more. > > Example: 2TB disk, default settings -> 275 million directory entries. > > this happens to also consume 275MM * 10 bytes = ~2.5GB of RAM just for the > directory entries. The easiest way to think of this is to think of our > directory entries as I-nodes. There's a fixed number of I-nodes, and you > can tweak it via that config, but doing so will be the same as doing an > "mkfs" (i.e. blow the cache). > > Note that more directory entries will consume a bit more disk resources as > well as RAM, when it syncs (and reads) the directory to (and from) disk. So > having a huge amount of unused directory entries is a waste too, but you > don't want to risk running out of them either. > > > -- leif > >
