Cache Drive - Read & Write Support

[TechDaddy]

**Note: This is high level question with simple samples. I'm not going to go into a in-depth explanation unless it's needed**

 

I have read up on the workings of the cache drive but there is one thing in there the does not make much sense to me.

 

I could not find anything about the cache drive improving read performance. Yes, I know that is something is in the cache, then there will be improved cache performance. What I'm talking about is making the cache drive work more traditionally as in, it caches all write data then immediately writes the data to the drives and does not wait for a scheduled (this can still help smooth writes to the pool). Then, there is some kind of algorithm (based on share preference) will see what you read a lot from an maintains a read cache for it. This would work great in a few PC Gaming Cafe's around town as to help them consolidate and save some cache ( ).

 

Last note: I know that you can store stuff in the cache and move it out of it when you are not using it so much. But this defeats the one of the main purposes of servers... automation!

[trurl]

The "read cache" feature has been discussed before but is not currently implemented. Not sure if it is on the roadmap. See here

[TechDaddy]

I have found a solution to what I was looking for. The only thing I was looking to cache are Games. I only have a 256GB in my main rig but with games going 40+ gigs in size, that can fill up fast.

 

So I just mapped a Games drive and called it a day. Then I though about going to lan parties and such and not having the fastest access to the network drive (connect via VPN). So, I would turn on Windows Offline Files and point it to my G Drive.

 

Then, I noticed (after a full sync) reads where bitchin fast again...

 

I did not fully understand the mechanics behind this feature so I found this: https://helgeklein.com/blog/2012/04/windows-7-offline-files-survival-guide/

 

HELL YES! I stumbled upon my own solution. It even see what is used most and caches against that!

[Helmonder]

**Note: This is high level question with simple samples. I'm not going to go into a in-depth explanation unless it's needed**

 

I have read up on the workings of the cache drive but there is one thing in there the does not make much sense to me.

 

I could not find anything about the cache drive improving read performance. Yes, I know that is something is in the cache, then there will be improved cache performance. What I'm talking about is making the cache drive work more traditionally as in, it caches all write data then immediately writes the data to the drives and does not wait for a scheduled (this can still help smooth writes to the pool). Then, there is some kind of algorithm (based on share preference) will see what you read a lot from an maintains a read cache for it. This would work great in a few PC Gaming Cafe's around town as to help them consolidate and save some cache ( ).

 

Last note: I know that you can store stuff in the cache and move it out of it when you are not using it so much. But this defeats the one of the main purposes of servers... automation!

 

The unraid cache drive does not work in the way you think it does. It sits in between the write process. A file beiing written is actually written to the cache drive and written back to the array nightly.. It does no write caching at all..

 

Second function of the cache drive is to keep files indefinately (mostly not media files, but additions to the unraid system, dockers, plugins, etc).

[TechDaddy]

**Note: This is high level question with simple samples. I'm not going to go into a in-depth explanation unless it's needed**

 

I have read up on the workings of the cache drive but there is one thing in there the does not make much sense to me.

 

I could not find anything about the cache drive improving read performance. Yes, I know that is something is in the cache, then there will be improved cache performance. What I'm talking about is making the cache drive work more traditionally as in, it caches all write data then immediately writes the data to the drives and does not wait for a scheduled (this can still help smooth writes to the pool). Then, there is some kind of algorithm (based on share preference) will see what you read a lot from an maintains a read cache for it. This would work great in a few PC Gaming Cafe's around town as to help them consolidate and save some cache ( ).

 

Last note: I know that you can store stuff in the cache and move it out of it when you are not using it so much. But this defeats the one of the main purposes of servers... automation!

 

The unraid cache drive does not work in the way you think it does. It sits in between the write process. A file beiing written is actually written to the cache drive and written back to the array nightly.. It does no write caching at all..

 

Second function of the cache drive is to keep files indefinitely (mostly not media files, but additions to the unraid system, dockers, plugins, etc).

 

Nope, that is how I understand the unRaid cache drive. I was hoping there was a way for it to cache commonly read items as well. IMHO, this would negate alot of die hard raid users to switch to unraid.

 

In my post before this, I stumbled upon a way to using my machines local SSD to cache network shares for faster reads.

[trurl]

Unless you have 10G ethernet the network will limit you about as much as drive read speed anyway.

[TechDaddy]

Unless you have 10G ethernet the network will limit you about as much as drive read speed anyway.

 

This is only half true. A SSD will provide MUCH better latency and be able to fill a 1Gb pipe while with small files (which games a ton of). Now, I don't have 300GB, 15k SAS drives, so I really doubt my consumer drives are going deliver SSD Performance with small file reads...