dev_guy

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  1. I agree for write once and read many times write performance is less important. But it's still frustrating having large copy operations taking days that would take hours even on a cheap RAID 5 NAS with the same drives. I understand the trade offs but they don't seem to be widely understood or sufficiently transparent. If Unraid was a free open source operating system I'd be less critical. But it's a proprietary paid OS I've paid hundreds of dollars for with both my servers and I'm disappointed.
  2. @JorgeB, thanks for the added info. Some of this is a bit counter-intuitive but I do now better understand how Unraid works, some of the trade offs, and appreciate your help. The drives in this server are a mix of 7200 and 5400 RPM drives. None of them are SMR drives. I would think the parity drive, and the drive currently being used to store the files being written, would dictate the speed not the other drives in the array which have next to nothing being written to them? I've booted this server into Linux and run benchmarks on all the drives. They're all much faster than I'm seei
  3. Preclearing is not the same as writing data. No parity is written for preclearing.
  4. Thanks for the link but I still don't understand why ALL the drives have to be spun up for writes to a share that only uses a few drives? The other drives seem to be needlessly spun up as they're not part of the share and show no writes with their reported used space remaining the same even after copying a large amount of data to the share? I understand that "turbo write" is working as documented, but that doesn't mean it makes any sense? Yes RAID 5 has some READ performance advantages but it's generally considered to be at a disadvantage during writes. So it doesn't have some unfa
  5. Thanks for your reply. I know USB 3 can be very fast but not with Unraid. My 40 MB/sec performance is with no other connections to the server besides the Unraid and Krusader GUI web interfaces. And the controller is the same LSI/Avago 8 port SAS in IT mode so many Unraid builds use and is capable of much better performance under other operating systems. The controller, and drives, are not the bottle neck. See my other post about turbo write. It needlessly spins up all the drives when only a few drives are assigned to the share in use. Even even with all drives spun up I still only
  6. Thanks to all for your suggestions. I have, for example, defined a share with only 3 of 8 drives. Enabling reconstruct write for the md_write_method (which seems to be the equivalent of "turbo write" in 6.8.3?) causes not just the 3 drives in the share to spin up but all 8 drives to spin up even though the other 5 drives have nothing to do with the share. Why? Unless I'm missing something that not only seems like a bug, but it defeats one of the major advantages of Unraid. Please correct me if I'm wrong, but "turbo write" seems to be broken? And even with "turbo write" enabled speeds only roug
  7. To constructor and itimpi I have been using Unraid for several years but my original server has 1TB of SSD cache and I've never tried to do large transfers from an external USB 3 drive with it. The newer server does not have cache and was mainly intended to consolidate all the stuff I have on large portable hard drives. I'm aware of the advantages with Unraid but some of those, such as mixing drive sizes, are now available on commercial NAS units if you want to go beyond RAID 5. But I didn't realize there's such a massive performance hit, without cache, even when you remove network
  8. They might be different but I don't think it's unfair to compare a low power NAS with similar drives in a protected array to Unraid in terms of write speeds. If I put say four 10TB drives in a commercial NAS running RAID 5 vs the same four drives into an Unraid server offering similar net storage and protection, I don't think it's unreasonable to expect at least somewhat similar performance especially when the Unraid box has several times the CPU performance, more RAM, etc. Obviously that's apparently not the case, but it's not like I'm comparing apples and oranges. The price of the drives far
  9. Was that for large sustained copying? Are you using Krusader? For me, Krusader initially reports optimistic transfer rates but they quickly decline to less than one third what you're seeing. I think the initial high rate is from RAM cache.
  10. There is no cache in the machine I'm referencing. My other Unraid system has a pair of mirrored 1TB Samsung SSDs for cache but not this one. Comparing Unraid write performance to RAID 5 is not an unfair comparison especially when Unraid is running on much higher performance hardware yet has less than half the write performance. As I understand it, RAID 5 has no performance advantage for writes as it has to compute parity roughly like Unraid does for writes. Basically 40 MB/sec for a direct transfer from a USB 3 drive capable of almost 3 times that speed, to fast Sata 6 Unraid drive
  11. Even when copying large 1+ GB files I'm only getting around 45 to 50 MB/sec copy rates using Krusader with an unassigned USB 3 external drive to my Unraid array of fast drives on fast hardware with lots of RAM. That's even a bit slower than I get over the network doing similar copies which are still really slow compared to most anything else. Is Krusader making things even worse? A decent USB 3 external drive can generally match or outperform Gigabit ethernet connections but apparently not with Unraid? Why not? With even a cheap low-end Qnap NAS, with a hugely less capa
  12. Thanks for the reply. I honestly don't know how to handle things. Even the latest 6.9.1, especially when done as an in-place upgrade, seems to have multiple problems causing many to revert back to 6.8.3. Yet my Samsung cache drives are being abused by 6.8. As I understand it just doing an online update can't reformat the cache drives to solve the excessive write issue which are all reasons why I was favoring a clean install.
  13. I have an Unraid server with a pair of mirrored Samsung SSDs as cache. As others have reported the drives are suffering from excessive writes and they also contain some VMs. Unraid 6.9 can likely fix the SSD excessive write issue but it seems only if I start over from scratch including reformatting the SSD cache drives? So I have two questions: How do I backup my VMs on the cache array and restore them after reformatting and upgrading to 6.9? And how do I do a clean 6.9 install on my paid registered flash drive without Unraid treating me as a new unpaid user?
  14. Thank you Trurl! The system I was doing the preclear on DID have bad RAM! It has 32GB or RAM so it took a while for it to show up in the memory test. So thanks for that tip! And, likewise, the same drives precleared successfully on different hardware. The drive that had logged a SMART error for a pending sector needed to be precleared with pre-read disabled so it would not abort before it ever got to the zero phase. During the zero phase the pending sector was recovered. Thanks also to S80_UK and Gfjardim for their input. Indirectly preclear helped me find bad RAM rathe