Cache Figures

[Bazza42]

I apologize if this has been asked and answered but I can't see such a topic since V6 went live.

My cache figures show 172/200 - should I be worried that this is impacting performance?

I assume that the figure is less a factor of 'space' and more of access times.

My data disk, which I guess is the important one, is an 80Gb SSD with 35.30GB free with 'only'
Windows 7 being the only other user.

My download disk, an USB2 2Tb external disk which is dedicated, shows 1.09Tb free

[itimpi]

The cache is the buffers that Newsbin uses for downloading chunks into. It is only going to ever impact performance if the free figure gets to 0.

As long as the free figure stays above 0, then Newsbin can continue to download even though it is also doing other things (checking/repairing/decoding etc). If Newsbin gets so busy that it cannot write the cache to disk fast enough, then when the value of free cache gets to 0, Newsbin will stop downloading until it can do some catching up and free some cache buffers.

If you want to allocate more RAM to the cache, then an entry can be set in the Newsbin configuration file (each buffer represents on average about 600KB of space)

[Quade]

172/200 means you're running 28 connections to the server. Each download worker thread acquires a block of data to work with out of the cache. When a chunk is downloaded, this block is handed off and the worker acquires another block from the cache. If you run out of blocks, it means that disk IO is bottlenecking the download speed. There's another related setting called the "MemCacheLimit" which allows you to tell Newsbin to cache the entire file in memory before writing it out. This also can improve performance. It defaults to 20 megs meaning all smaller files are downloaded to RAM and written out in one block when done. That's why you might not see any NB2 files when you you're downloading smaller files.

I'll write something up about these settings and what they do.

[Bazza42]

Many thanks to you both for your comprehensive response.