Use share minimum limits also for cache


Torben

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Hi all,

 

I searched the forum, but didn't find anything regarding the share limits and the cache drive (except that there are different settings 🙂 ).

 

After my cache drives (SSDs) were completely filled up during a copy process (that of course failed), I investigated and found out that there's a separate setting for the cache. The problem is that I sometimes copy large files (85+GB) and use the cache to have fast transfer speeds. So I have set the cache and relevant share minimums to 90GB. Now the copy process continues, but e.g. the Dockers also write their 4kb log files to the array. This isn't great, especially since I have to stop all Dockers at the end of the "normal" Mover process to get the data written by the Dockers back on the cache drives.

 

If there's a technical reason why it can't be done, I would be interrested to know why.

 

Otherwise: Feature request. 🙂

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I believe that when writing to the cache Unraid uses the larger of the cache Minimum Free Space and the User Share minimum Free Space value when deciding whether to write a file to the cache for a share with Use Cache=Yes.   In your case you may be able to handle the case of large media files by having a higher value for the share than for the cache.    This would allow files for a different share with a smaller value to continue going to the cache.

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That's what I thought how it would work - but it doesn't (not only for me, also for a colleague). :-)

 

I had set all the Share minimum free space settings to what they have to be (like 4GB for one, 90GB for the other and so on) and then some day ran into the problem that not all data was copied, since the cache was full (and with "full" I mean like "0kb free-full"). The Cache setting was default, I guess it's 2GB, and there was like 10GB free - but the file to be copied next was 14GB, so unRAID wasn't able to fit it on the Cache and the copy process failed. That's where I also changed the appdata-Share to "prefer" instead of "only", so that my dockers still continue running when the Cache is full. ;-)

Edited by Torben
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Hello again,

 

I tried to reproduce it yesterday. While doing that, something weird happened: I misconfigured my test-share (0kb minimum free), so the cache drive filled up until 2GB and the copy process failed - expected behavior. I stopped the copy process from within Midnight Commander and instantly 250 GB were freed up on the cache drive (the file being copied was ~70GB, not 250GB in size). I pulled the diagnostics and the array "died". So I rebooted and it took like 3 reboots to get the server up and running again. After that I changed the share minimum to 90GB and left the cache minimum at 2GB...and it worked, just as you said. I the heck don't know what happened, maybe wrongly reported data regarding the cache free space or so? Anyways, I now know that it's working as I would have assumed - and as you said (based on share settings), so this "Feature Request" can be closed. I'll check during the normal copy processes if it happens for the old shares and if it does, I'll open a bug/general support post.

 

Thanks again for your time!

Edited by Torben
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