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Prefetch Settings


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In regards to the 4 prefetch settings, can we get some information on what they do so we can correctly optimize the prefetcher (PF) ?

 

Enable prefetecher - hopefully this checkbox either enables or disables the feature ;)

 

Prefetch tigger - does this mean the PF kicks off when only 1MB is left in the PF?

 

prefetch forward - does this mean how much it will download each time it goes out to PF the file?

 

prefetch time window - is this a timeout ?

 

 

thanks

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Enable prefetecher - hopefully this checkbox either enables or disables the feature ;)

Yes, toggles its state.  :)

Prefetch trigger - does this mean the PF kicks off when only 1MB is left in the PF?

I believe this is the amount of data read before it triggers prefetching. So, yes, I beleive so.

 

I'll ask Alex for clarification here. 

prefetch forward - does this mean how much it will download each time it goes out to PF the file?

This is how much in advance it will prefetch (or "buffer") for the reads.  

 

 

prefetch time window - is this a timeout ?

Yes, this is for how long the prefetched data will remain in the cache (buffered). If it's not needed after this, it will clear it from the cache.
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  • Prefetch Trigger - How much data needs to be read sequentially (not necessarily in order), to trigger a prefetch forward.
  • Prefetch Forward - How much data to download when Prefetch Trigger occurs.
  • Prefetch Time Window - How long to keep the prefetched data temporarily pinned in order to prevent the cache from trimming it (applies mostly when the cache is Off). Also, how long to keep track of each read request, in order to determine when Prefetch Trigger occurs.
Increasing or decreasing with change how aggressive the data is fetched.

Increasing the Prefetch Time Window can be increased if the prefetching is extremely aggressive (or if you're doing a lot of stuff taht will trigger it), but at the cost of CPU overhead.

 

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Do you have some "recommended" settings that I could try?  I currently use netdrive with my amazon cloud drive but it doesn't have built in encryption.  I can upload at a constant 50 to 90MB/s to the amazon cloud drive with netdrive.  I am sure I can reach close to those speeds with Stablebit CloudDrive I just need to tweak some performance settings.  Any help would be greatly appreciated.

 

P.S.  I am running a 1gbit connection with 4 Hard drives and 32GB of memory.

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Well, we hope that the build int defaults are "reasonable".

 

However, this vastly depends on your internet connection. 

 

One thing to keep in mind here, is that the chunk size and local cache size for the drive will also influence this.

 

First thing, if you're going to be using the CloudDrive a lot (for reads, or writes or both), then a larger cache size will definitely benefit you.  If you have a fast drive or don't mind "thrashing" a SSD, that may be great for the cache.  

 

After that, the prefect forward setting and the prefetch time window settings are the ones that matter most.

Setting the "forward" value increases how much data it prefetches. Setting the time window is how long it keeps that data.

 

If you increase one, you will definitely want to increase the other, to make sure that the data actually stays long enough.

 

 

 

 

As for increase the actual speed, the advanced settings may work better for that:

http://wiki.covecube.com/StableBit_CloudDrive_Advanced_Settings

 

The IoManager option is what you want. The settings here should be pretty obvious.

Increase the read/write threads means more concurrent connections.

Increasing the connection limit increases how many option HTTP(S) connections we can have.

The timeout, well, depends. Etc.

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