February 12Feb 12 I have 6TB SSD (3 X 2TB) for a Cache and 10X HDDs (Seagate and WD 7200rpm). CPU is Intel 12700K, GPU is nVidia 1080Ti, 128GB RAM and my entire network is all 10G.The performance issue I’m running into is when start multiple copy/paste from my Win11’s PCs to the UnRaid NAS. The files I copy and paste aren’t that many (maybe 30 total with sizes from 1GB to 63GB … mostly video files). The initial transfer speeds is good at about 800-900 MB/s for about 10-15 seconds then deteriorates to 60 MB/s. If I start parallel copy/paste operations each operation will slice down … example 60MB/s then add two more copy/paste operations and all 3 operations are now down to about 20MB/s.So when I monitor Unraid, the CPU threads don’t seem to be overloaded at all and RAM usage is well below max 128GB. My Cached SSD usage is below 3TB.I’ve used the optimization tool which helped a little but multiple transfers still brings my Unraid NAS to a crawl.To validate there is nothing wrong with my 10G network adapters, I do the same transfers across two of my PCs on my network and they sustain about 1000 MB/s and never deteriorate and complete the transfers MUCH faster.So what can I do to make Unraid faster … it just seems incredibly slow and the parity checking takes FOREVER (160TB with two parity drives so about 120 TB usable and 57 TB currently available, using about 63TB).My options?More RAM?Better SATA controller?Hardware RAID controller with RAM expansion? Driver support?More SSD Cache?Better CPU?All suggestions welcome on how (if) to make Unraid faster?Rob.
February 12Feb 12 10 minutes ago, RobAinscough said:I have 6TB SSD (3 X 2TB) for a Cache and 10X HDDs (Seagate and WD 7200rpm).How are these setup, array or pools? Or better yet, post the diagnostics with the array started.
February 12Feb 12 Author In the office now, will post diagnostics tonight.Actually 11X HDDs (2 parity) in an Array. 3X 2TB SSDs are Pooled Cache.
February 12Feb 12 Are those copies going to cache or straight to array? What's the source? Parallel copies is never a good thing to do, especially if either the source or destination is an HDD it will always be way slower than doing them one after the other.
February 12Feb 12 Author Will post more details tonight.Like I said, no problem doing the exact same parallel copies between two PCs, they drop a little (400-500MB/s) but not to 20MB/s or less. So I know this is not a network/NIC issue but something to do with Unraid and the hardware in my NAS.The copies are (and should be) going to Cache (the SSD Pool) then to the array … I see the SSD Cache being used.Sorry, but not going to sit around for hour waiting for one copy to finish and then start another and repeat 30 times ;)
February 12Feb 12 Seems typical for writes to the array and not cache. Diagnostics might tell us more.https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array/overview/#array-write-modesIf this is the initial data load, you could run without parity until completed.
February 12Feb 12 Author Hmmm … what you describe would make sense … for some reason it stops writing to the cache and then writes direct to Array? Wonder if the cache isn’t being flushed after transfer completes to the array?No, this is not an initial dump. Per my post, usually once a day 1-30 files totaling a max of about 500GB … well below my 3TB Cache pool with parity (6TB). Yes, will get those diagnostics up later today.
February 12Feb 12 6 minutes ago, RobAinscough said:for some reason it stops writing to the cache and then writes direct to Array?Likely your minimum free space settings on the share in question are set a bit too high. 2 hours ago, RobAinscough said:Sorry, but not going to sit around for hour waiting for one copy to finish and then start another and repeat 30 times ;)Can use something like Teracopy to queue all ops and then run them sequentially.
February 12Feb 12 8 minutes ago, RobAinscough said:for some reason it stops writing to the cache and then writes direct to Array?https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/cache-pools/#minimum-free-space-for-a-cache-pool10 minutes ago, RobAinscough said:Wonder if the cache isn’t being flushed after transfer completes to the array?Mover runs on schedule, default is once per day in the middle of the night. Mover is intended for idle time. It is impossible to move from fast cache to slow array as fast as you can write to cache. Trying to write and move at the same time makes things worse. Making it move more frequently is usually not a solution.If you need to write more than cache can hold between moves, don't cache.
February 12Feb 12 Author I’ll have to check my Mover schedule. I typically move large files once a day at night around 10pm. Like I said earlier, the files I move never exceed the Cache (3TB) … in fact rare they even hit 1TB.Mover is definitely something I need to investigate and come up with a good schedule.EDIT: great link, thank you … I have no idea what my minimum free space setting is for the Cache. Edited February 12Feb 12 by RobAinscough
February 13Feb 13 Author Ok, the issues seems to be that the share I’m copying my large files to isn’t setup for Cache to Array. And I’m starting to recall why it is setup that way … I read somewhere that Plex Server (which I have installed) needs to point to an Array share and NOT a Cache to Array share. I vaguely remember setting the share (that Plex uses for all the movies/music etc.) to Cache to Array and Plex lost all context of what I had setup and showed me an empty Plex library when I brought up the Web UI. In fact, as I recall, it was a complete disaster and I ended up re-installing plex after I set the share back to just Array.Copy of medias-diagnostics-20260212-2046.zipAnyway, diagnostic files.
February 13Feb 13 If you are writing to the array, and once the RAM cache is full, 60MB/s is typical for default write mode; you should get a nice bump if you enable turbo write, at the expense of all drives spinning up for writes.https://forums.unraid.net/topic/50397-turbo-write/But keep in mind that there's no striping with the array, so it's still limited by the single disk write speed, if you need more speed, consider using a ZFS RAIDZ pool instead, but that also has its own drawbacks.
February 14Feb 14 Author On 2/13/2026 at 3:26 AM, JorgeB said:...if you need more speed, consider using a ZFS RAIDZ pool instead, but that also has its own drawbacks.Can you fill me in on ZFS RAIDZ pool?Implications for my existing setup? Quick read and it seems I need to format the new ZFS RAIDZ pool ... no ability to migrate all my existing 67TB of data?Benefits?Limitations?Thanks, Rob.
February 15Feb 15 11 hours ago, RobAinscough said:Quick read and it seems I need to format the new ZFS RAIDZ pool ... no ability to migrate all my existing 67TB of data?Correct.11 hours ago, RobAinscough said:Benefits?Limitations?Main ones are mentioned here (performance and other limitations apply to any file system on the array):https://forums.unraid.net/topic/131857-soon%E2%84%A2%EF%B8%8F-612-series/?do=findComment&comment=1243850
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