RobertP Posted February 17, 2020 Share Posted February 17, 2020 I added an 1 TB SSD cache drive (previously I had no cache drive), but it is not being used. It IS functional, I’ve moved “appdata” and “system” over to it, so I know the drive is OK. Side note question – why is it recommended to put appdata and system on the cache drive? I did a pre-clear, then assigned it as cache drive and did a format. I’ve moved 2 folders to the cache drive (per SpaceInvader One’s instructions - https://www.youtube.com/watch?v=ij8AOEF1pTU ). I did NOT move domains ‘cause I don’t do much with VMs and don’t really want the couple VMs that I’ve played with to be consuming a big chunk of the cache drive. The main thing this unRAID server is for is holding backup images of various different computers around the house – and those backup images can be big so I want the cache “wide open”. I’ve set one of my user shares to “Use Cache” setting of YES. I’ve gone into the main SETTINGS tab, GLOBAL SHARE SETTINGS and set the USE CACHE DISK to YES. I’ve played around with a few different sizes on the “Min free space” – right now it is set to 1MB But when I run a backup that uses that share, the backup does not get sent to the cache drive first. I’ve also tried manually copying some files of various different sizes to that share – the cache drive is not getting used. The copies go straight to the user share. Since adding the cache drive, I've seen no speed gain in the copies, and after the copy if I look at MAIN, Cache, VIEW it does not show anything there (other than the 2 folders I manually moved). I click MOVE NOW and it is done in a second. What is this newbie missing? ur1-tower-diagnostics-20200217-0028.zip Quote Link to comment
superloopy1 Posted February 17, 2020 Share Posted February 17, 2020 (edited) With cache value of yes any writes to share with that value should go onto cache first and then move to the array when mover is enabled. I would write to a share with cache set to yes and then watch for the write activity on the main page. It SHOULD be against the cache disk and parity obviously, only. First line of attack ... no doubt someone will be along with plenty of other advice ... Edited February 17, 2020 by superloopy1 Quote Link to comment
RobertP Posted February 22, 2020 Author Share Posted February 22, 2020 Nope - I've got my user share "UR-BU-i7" set to USE CACHE of YES. I've got my SETTINGS, USE CACHE DISK set to YES. Doesn't matter if I do a backup to that share, or if I manually copy a small file (3KB) or few big files (four 1GB files), nothing goes to cache. I've tried copying to the "root" of "UR-BU-i7" and I've tried copying to a folder under that. Nothing happens to cache. After I do the copy, on the MAIN tab I click on the VIEW icon to the far right of the CACHE device - the files I copied are not showing up. Also, the cache's USED and FREE space is not changing. Copying the same files to a user share that is set to USE CACHE of NO - the copy speed is the same. Do I need to MANUALLY create a "UR-BU-i7" on the cache first? (If yes, then HOW?) As I said, I was able to MOVE the appdata and system folder to the cache using mover ("use cache" is set to PREFER for them). Quote Link to comment
Hoopster Posted February 22, 2020 Share Posted February 22, 2020 Side note question – why is it recommended to put appdata and system on the cache drive? It is recommended to store appdata, system, domains, etc. on an SSD cache drive or unassigned device so docker container or VM activity does not cause array drives to spin up or remain spun up unless they are actually needed to write or access files. Also for performance reasons for docker and VMs. For future reference it is not necessary to preclear SSDs. That just results in a lot of unnecessary writes to the SSD. Now, not to be Captain Obvious, but, when you changed the share cache setting to Yes, did you click on the Apply button to save that change? Sent from my iPhone using Tapatalk Quote Link to comment
RobertP Posted February 26, 2020 Author Share Posted February 26, 2020 lol - yes, I clicked APPLY. But that is a good question to ask. BUT - problem solved! The SSD is a 1TB drive. With the system files on it, there was about 980GB or so free. Because I use my unRAID as a place to store my backups, and because some of those backups can be quite large, I had that share set to MOST-FREE and, ****more importantly**** I had the Minimum free space set to 1TB. Since the cache would not hold 1TB, it apparently went straight to the share. I dropped the minimum free space down to 800GB and now it is using the cache! Be interesting to see if this speeds up my next weekly backups next weekend! Quote Link to comment
lemoncurry Posted March 16, 2020 Share Posted March 16, 2020 Ive got the same issue, but with a 120G SSD cache. Checked all the share settings Ok. Cache disk has the appdata and system folders. the Domain and ISOs shares are not used as the box cant run VMs. The only share is "Backup" . Writing files to the Backup share never uses cache! Share is set to High-water, 1MB min, Cache: Yes. What should I look for to troubleshoot this? Quote Model: TS-669-Pro M/B: Intel Corporation Granite Well Version FABA - s/n: 1.0 BIOS: Phoenix Technologies Ltd. Version QU95PR57. Dated: 06/28/2013 CPU: Intel® Atom™ CPU D2700 @ 2.13GHz HVM: Not Available IOMMU: Not Available Cache: 32 KiB, 512 KiB Memory: 3 GiB DDR3 (max. installable capacity 4 GiB) Network: bond0: fault-tolerance (active-backup), mtu 1500 eth0: interface down eth1: 1000 Mbps, full duplex, mtu 1500 Kernel: Linux 4.19.107-Unraid x86_64 Quote Link to comment
trurl Posted March 16, 2020 Share Posted March 16, 2020 2 minutes ago, lemoncurry said: What should I look for to troubleshoot this? Go to Tools - Diagnostics and attach the complete diagnostics zip file to your NEXT post. Quote Link to comment
lemoncurry Posted March 16, 2020 Share Posted March 16, 2020 Heres the Zip unnap-diagnostics-20200317-0126.zip Quote Link to comment
trurl Posted March 16, 2020 Share Posted March 16, 2020 Post a screenshot of Settings - Global Share Settings - Cache Settings Quote Link to comment
lemoncurry Posted March 17, 2020 Share Posted March 17, 2020 Hi, Global Cache set to YES, Min. free space: 200,000,000, which I incorrectly assume as Bytes, but apparently its 1024byte blocks (confusing)! So that means the global floor is set to >200GB! I don't recall ever looking at this setting so it must be the default. Q1 - Is 200000000 the default upon installation, if so why so high ? Q2 - Why do global settings override local settings, isn't that the wrong way around ? I've set the Global Share Settings - Cache Settings - Min. free space: 100MB Now fixed. Quote Link to comment
lemoncurry Posted March 17, 2020 Share Posted March 17, 2020 (edited) Thanks for the very fast assistance. Edited March 17, 2020 by lemoncurry Quote Link to comment
trurl Posted March 17, 2020 Share Posted March 17, 2020 That was definitely not the default. I think that was 3 zeros too many. The Minimum Free for cache is similar but different from Minimum for each user share. Each user share has a Minimum Free. If an array disk has less than Minimum when Unraid decides which disk to write a file to, it will choose a different array disk. You should set Minimum Free for each user share to larger than the largest file you expect to write to that user share. Once Unraid has chosen a disk to write the file it will try to write the whole file to that disk even if it runs out of space. For Cache Minimum Free, if a user share is cache-yes or cache-prefer, then if cache has less than minimum when Unraid decides which disk to write a file to, it will choose an array disk instead of cache. This is sometimes called "overflowing to the array". Note that a cache-only user share will not overflow (and a cache-no user share will not write to cache anyway). Similarly, you should set Minimum Free for cache (in Global Share Settings) to larger than the largest file you expect to write to cache. Quote Link to comment
lemoncurry Posted March 17, 2020 Share Posted March 17, 2020 Ahh, yes, I got confused between Cache settings and Array share settings. Obvious now really. Maybe I did add the zeros back when I first set it up, assuming the setting is bytes. ie 200000000=200MB not 204GB! Cheers. Thanks for the very fast assistance. Quote Link to comment
itimpi Posted March 17, 2020 Share Posted March 17, 2020 3 hours ago, lemoncurry said: Ahh, yes, I got confused between Cache settings and Array share settings. Obvious now really. Maybe I did add the zeros back when I first set it up, assuming the setting is bytes. ie 200000000=200MB not 204GB! Cheers. Thanks for the very fast assistance. If for any reason you need to edit that field it is much easier if you use one of the suffixes to specify the units being used. Quote Link to comment
Ben de Vette Posted February 1, 2023 Share Posted February 1, 2023 (edited) Maybe old news, but my cache started working only after I first started mover (MOVE) via the main page. Edited February 1, 2023 by Ben de Vette Quote Link to comment
trurl Posted February 1, 2023 Share Posted February 1, 2023 3 minutes ago, Ben de Vette said: cache started working only after Almost certainly some misunderstanding somewhere. If you need more advice, attach diagnostics to your NEXT post in this thread. Quote Link to comment
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