Some files are being cached twice.
By Colonel ONeill | January 26th, 2009 | 10:54 pm
With two cache devices, a few files are being cached in both devices.
1. Wouldn’t this be a waste of space? Couldn’t it be cached in one device only?
2. Does eBoostr move more commonly accessed files to a faster cache device?
3. When eBoostr does it’s cache build, does it adaptively select which files to keep and which files to replace in the cache?
Does it keep track of how many times each file is accessed when caching is active? If so, does it use this data to sort cache files by access hits? It would be cool if it would keep files accessed above a certain threshold, (e.g. at a cache build, keep the 50% most accessed, and would rotate cached files until it finds that optimum balance?)
Jan 27, 2009
Some of us have been asking the same questions…
Where are the statistics used to determine which files are cached? We want to use these statistics to determine the best possible configuration for a boost-device. There was discussion earlier which demonstrated only files up to a certain size benefit from boosting, depending on the flash media’s specs.
Not only do we want to see numbers (at least provided by a ‘debug’ mode so it doesn’t hinder performace during normal operation), but we’d like to see a way to configure different types of boost devices. For example, RAM doesn’t need to have file size parameters imposed, but flash might. I might want larger files cached in RAM and the smaller ones on flash in order to get the best performance at the best efficiency of available storage.
At this point, however, I have not seen a single response from eBoostr to the questions regarding statistics, how eBoostr determines which files are cached, or whether they’re interested in publishing detailed configuration scenarios!
I’ve briefly look for a utility to monitor Window’s file usage (access count, access time, seek time, transfer rates, etc.) and compile the stats, but I have yet to find one for XP 64-bit.
Anybody have some ideas?
Jan 27, 2009
I know Filemon does it for x86’s. Never actually used a 64-bit OS. Could you run it in compatibility mode?
Jan 27, 2009
I think FileMon does monitoring only, not statistics (like counting hits or access times). I’ll check it out again just to be sure, maybe there’s a useful logging feature I didn’t see!
Thanks.
Jan 29, 2009
1. eBoostr stores each file on every physical cache device. Each read is divided between several devices and processed simultaneously to gain additional speed. Files that are stored in memory cache are not duplicated anywhere else.
2. See 1.
3. Yes, eBoostr updates cache contents based on file read statistics gathered by the driver which monitors all requests.
eBoostr stores stats for each file even if caching does not active. So it easy to get top 1000 (just example) files which have greater (read size/file size) ratio than others. Such files are placed in cache during cache build.
BTW we are using SQLite to store these stats (the file “filestat.dat”), so if you are serious about exploring it then you can use any SQLite viewer to examine the stats. Please note that database format is completely undocumented.