how is cache used?

[smaka510]

I have a bunch of shares on my server. I needed to copy well over 5tb when I first started with unraid. this was much more than the cache drive max complicity, so I set the share to not use cache. But now that all that is done and I have 10gb P2P connections with my unraid server I went and turned the cache back on.

 

How is the cached used? Is it only used to copy data to the server or is it also used if I want to watch a movie in plex or kodi?

[JorgeB]

Cache is not used for caching array reads, but it has different uses, see here for more info:

 

https://forums.lime-technology.com/topic/46802-faq-for-unraid-v6/?do=findComment&comment=537383

 

[kizer]

If you don't want to use your Cache Disk you can copy files directly to disk shares to avoid involving your Cache Drive.  ie. Disk1, Disk2 and so forth. 

[smaka510]

I have a new 10gb p2p connection with my NAS.

The cache drives are 2x Samsun EVO 850's 250gb SSDs - in raid 0

I have my shares set NOT to use the cache.

 

I noticed the faster writes to the NAS, but the reads are unaffected (because files are stored on HD). My plex directories look like this:

\\server\movies

\\server\tv

\\server\kidsmovies

 

I want to make a temp location on the cache for reading that looks like this

\\server\cache\temp\movies

\\server\cache\temp\tv

\\server\cache\temp\kidsmovies

 

Plex monitors both normal shares (on HDDs) and temp folders on cache (SSDs raid 0).

 

I have a VM that runs a series of powershell scripts that will move anything found in "\\server\cache\temp\movies" older than 90 days to the equivalent share on the normal storage "\\share\movies".

 

The idea is that all of the most recent stuff added to plex will be temporary stored on the SSDs (cache) for quick access. IT will have likely viewed these movies/tv within the 90 days, in which case it can be moved to the slower HHDs.

 

Can the Cache be used this way? Should I install a dedicated set of drives for this? Will this mess with the "file mover" at all?

Edited November 29, 2017 by smaka510

[trurl]

On 11/27/2017 at 6:47 PM, kizer said:

If you don't want to use your Cache Disk you can copy files directly to disk shares to avoid involving your Cache Drive.  ie. Disk1, Disk2 and so forth. 

It isn't necessary to enable Disk Shares to bypass the cache. You can just configure the User Share to not use cache. I don't recommend using Disk Shares.

[trurl]

8 minutes ago, smaka510 said:

I have a new 10gb p2p connection with my NAS.

The cache drives are 2x Samsun EVO 850's 250gb SSDs - in raid 0

I have my shares set NOT to use the cache.

 

I noticed the faster writes to the NAS, but the reads are unaffected (because files are stored on HD). My plex directories look like this:

\\server\movies

\\server\tv

\\server\kidsmovies

 

I want to make a temp location on the cache for reading that looks like this

\\server\cache\temp\movies

\\server\cache\temp\tv

\\server\cache\temp\kidsmovies

 

Plex monitors both normal shares (on HDDs) and temp folders on cache (SSDs raid 0).

 

I have a VM that runs a series of powershell scripts that will move anything found in "\\server\cache\temp\movies" older than 90 days to the equivalent share on the normal storage "\\share\movies".

 

The idea is that all of the most recent stuff added to plex will be temporary stored on the SSDs (cache) for quick access. IT will have likely viewed these movies/tv within the 90 days, in which case it can be moved to the slower HHDs.

 

Can the Cache be used this way? Should I install a dedicated set of drives for this? Will this mess with the "file mover" at all?

 

The best approach for what you want to accomplish is to make a User Share named 'temp', and set it to cache-prefer. Then anything written to 'temp' will be written to cache if it has the capacity, with overflow going to the array. Be sure to set Minimum Free for the temp share and for the cache disk. Minimum Free MUST be set larger than the largest file you will ever write.

 

Then your script idea for moving to the more permanent locations would be fine, though you could also script and schedule this directly in unRAID with the User Scripts plugin, for example.

[trurl]

Also, if you use the approach I recommended, the path to the files in the temp User Share would just be \\server\temp. That way it would include both the temp files on cache, and any overflow that wound up on other disks. And there would be no reason for you to use disk shares, which I don't recommend.

[c3]

2 hours ago, smaka510 said:

Plex monitors both normal shares (on HDDs) and temp folders on cache (SSDs raid 0).

 

I have a VM that runs a series of powershell scripts that will move anything found in "\\server\cache\temp\movies" older than 90 days to the equivalent share on the normal storage "\\share\movies".

 

The idea is that all of the most recent stuff added to plex will be temporary stored on the SSDs (cache) for quick access. IT will have likely viewed these movies/tv within the 90 days, in which case it can be moved to the slower HHDs.

This keeps files under 90days old on RAID0, not a good idea.

[kizer]

3 hours ago, trurl said:

It isn't necessary to enable Disk Shares to bypass the cache. You can just configure the User Share to not use cache. I don't recommend using Disk Shares.

 

There is nothing wrong with using Disk Shares as long as you Transfer Disk Shares to Disk Shares and don't even think about Mixing Disk Shares with User Shares, which we all know gets really UGLY if done. I only suggested it as a if needed, but I wouldn't recommend using it all the time unless you have a very specific need. 

 

Personally I'd just use the Cache drive and have Plex point at your shares and when the files are moved they are moved to your array to limit your chance of loss. Sure the first day they would be accessible very fast, but you are increasing your chances of loosing data for 90 days.