I just added a 128 GB SDD drive as a cache to my server.  I tested it by copying a DVD folder and I got the usual 20 MB/s!  I then looked in /mnt/cache and it is empty.  I should be able to see any files copied to the array in /mnt/cache before the mover runs, right?

 

Attached are screenshots from the GUI, can anyone tell me what is wrong?  Thanks.

The settings look correct to me.  Where did you copy the file to?  Did you copy it to \\tower\user\Videos or to \\tower\diskX\Videos?

 

I also have a cache drive (a spinner though, not an SSD), but up until recently have only used it for apps.  I can easily write to the cache at 80+MB/s.  I recently enabled the cache drive for one of my shares and wrote an 8GB file to the share.  It did in fact get written to the cache drive, but for whatever reason the write speed I got was no different than my normal array write speed, about 40MB/s.

Did you enable the use of the cache drive in the 'SETTINGS' tab?

Sorry, I've got Dynamix installed, but the tab in the standard interface is either 'Settings' or 'Shares'.

See this snapshot of the Dynamix screen...if I recall correctly, the 3 sub-tabs are on one page in the regular GUI.

The settings look correct to me.  Where did you copy the file to?  Did you copy it to \\tower\user\Videos or to \\tower\diskX\Videos?

 

I also have a cache drive (a spinner though, not an SSD), but up until recently have only used it for apps.  I can easily write to the cache at 80+MB/s.  I recently enabled the cache drive for one of my shares and wrote an 8GB file to the share.  It did in fact get written to the cache drive, but for whatever reason the write speed I got was no different than my normal array write speed, about 40MB/s.

 

I wrote the DVD folder to \\Videos\Movies\DVD, which is in the user share Videos.

Not sure how to proceed from here.  Everything looks correct as far as I can tell from the documentation.  Maybe something about using and SDD is the problem?

I've an idea here. Dont ssd's use a default blocksize of 4K blocks? I think that your setting of 40000000 without specifying an ACTUAL freespace level defaults to'number of default blocks' which if using a fixed disc would be1K and your ssd is too small using that setting as there would need to be 160GB  of space left to allow it to be used. Change your minimum free space setting to '40GB' (i assume you want to have at least a blurays worth if free space using that setting) instead of '40000000' and give it a go, see if that helps.

 

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I've an idea here. Dont ssd's use a default blocksize of 4K blocks? I think that your setting of 40000000 without specifying an ACTUAL freespace level defaults to'number of default blocks' which if using a fixed disc would be1K and your ssd is too small using that setting as there would need to be 160GB  of space left to allow it to be used. Change your minimum free space setting to '40GB' (i assume you want to have at least a blurays worth if free space using that setting) instead of '40000000' and give it a go, see if that helps.

 

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Brilliant catch

Lets hope it works. Just seemed a possibility to me.

 

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I've an idea here. Dont ssd's use a default blocksize of 4K blocks? I think that your setting of 40000000 without specifying an ACTUAL freespace level defaults to'number of default blocks' which if using a fixed disc would be1K and your ssd is too small using that setting as there would need to be 160GB  of space left to allow it to be used. Change your minimum free space setting to '40GB' (i assume you want to have at least a blurays worth if free space using that setting) instead of '40000000' and give it a go, see if that helps.

 

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That did it.  Copying now puts the files on the cache disk.  The I copied a 1 GB file and now get about 55 MB/s.  This is still slower that I should be seeing though.  Maybe I will try moving the SSD to a SATA port on the MB (now on a Supermicro PCIe HBA).

 

Thanks for your help.

I've an idea here. Dont ssd's use a default blocksize of 4K blocks? I think that your setting of 40000000 without specifying an ACTUAL freespace level defaults to'number of default blocks' which if using a fixed disc would be1K and your ssd is too small using that setting as there would need to be 160GB  of space left to allow it to be used. Change your minimum free space setting to '40GB' (i assume you want to have at least a blurays worth if free space using that setting) instead of '40000000' and give it a go, see if that helps.

 

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Brilliant catch

 

40000000k = 40GB  The 'k' is implied. It shouldn't make a difference. Glad it's working.

I've an idea here. Dont ssd's use a default blocksize of 4K blocks? I think that your setting of 40000000 without specifying an ACTUAL freespace level defaults to'number of default blocks' which if using a fixed disc would be1K and your ssd is too small using that setting as there would need to be 160GB  of space left to allow it to be used. Change your minimum free space setting to '40GB' (i assume you want to have at least a blurays worth if free space using that setting) instead of '40000000' and give it a go, see if that helps.

 

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Brilliant catch

 

40000000k = 40GB  The 'k' is implied. It shouldn't make a difference. Glad it's working.

 

Not quite right.

 

Without specifying 'KB' 'MB' or 'GB' the figure specified as a minimum setting defaults to 'number of disc blocks' and as SSDs use a default block size of 4KB then a setting of 40000000 would require 160GB of freespace, greater than the OP's SSD.

 

A setting of '10000000' would have worked in this case as has a value of '40GB'.

 

There is no 'implied K' unfortunately.

 

This link seems to clarify things ...

 

http://lime-technology.com/wiki/index.php/Plugin/webGui/Cache_Settings

 

Glad i could help .... i'm new to unraid and just 'happened' on this cache setting recently thats why it was in my mind.

 

Maybe this difference in the setting for SSDs as opposed to a 'spinning' disk needs to be included in the FAQ?

 

 

Update ... i've jut reread that FAQ page and I've come to the conclusion that it is badly written. It DOES say 'number of 1024 byte blocks' yet goes on to use 'number of data blocks'. Possible that it wad written before SSDs came in and needs an update to reflect the 4K blocksize of SSDs?

 

Anuone using an SSD as cache drive ... what are your settings?

 

 

 

 

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