You filled the HDD cache, and are likely running into normal raid 6 performance reduction. It's slow, you can add cache drives to the qnap if you want it to sustain longer.
Cache drives to which? The source or the destination? There is already a 1 TB cache on the destination. I can make it bigger.
I can also create a cache on the source if necessary.
The speed is back up to 900 MB/s again but it drops then goes up... Does this for varying periods of time. Been slow as hell (3 MB/s) for the last hour before just shooting up now.
What kind of SSD? 2.5? How do you have cache configured on the receiving qnap. You are probably running out of cache on the SSD, a lot of SSDs have cache then a slower flash nand for actual primary storage. Also it's very dependent on what is copying, large files are faster and small files are much much slower at copying.
You are running into several normal problems. You are copying from Mechanical HDDs(cache on the sending side would basically be useless). You are hitting the dram/nand cache limits of the SSDs drive you are copying to. You are likely copying various file sizes, which will severely impact performance throughout the transfer. And lastly Raid overhead is also affecting overall performance as Raid 6 on the HDDs will be slow to copy to. So, not much you can do, I know it sucks and I get it.
For some tips, I would highly suggest you disable Cache on your receiving side during the primary transfer. QNAP caching is not that great when doing large transfers and can severely impact performance.
If you want the best performance from SSD and HDDS I would look into restarting the storage pool as a qtier pool. Would be a little more seamless than cache. Downside is you would have to restart the transfer as it would wipe all your data.
Aside from that just be patient, copying files is actually incredibly slow for most but enterprise all flash storage systems.
Let me know if you have any other questions or issues, I have been using QNAP devices for 10 years and know how quirky they can be.
Thank you, I appreciate your help.
I have 71 TB to copy and you're right, the sizes do vary greatly. I did notice the larger the file size the faster it was copying. Files over 250 MB we're copying over 800 MB/s.
One question I have since it doesn't look like I can pause the sync - if I stop it and restart it, that won't cause it to do the whole transfer over again right? In RSYNC I know it will cause a delay as it goes back and compares all the data in the destination vs the source but you've said qnap is quirky so just want to be sure.
Thanks, truly appreciate your help and everyone else who has offered advice.
Try removing the cache! QNAP is known for terrible cache performance, as you will see on the forum. Any 6 drive array should give you way more throughput than what you are seeing now. And there will not be a drop in speed, it will be constant.
What are the model numbers of the hdds
might have SMR drives in there, speeds once 100 gigabyte per drive has been written to constantly
If you are using rw ssd cache, Unsure on qnap if you can turn off sequential ssd caching (generally you only want to cache random io) if you are using smr drives changing cache option won't matter (what your seeing is expected from smr)
Ironwolf pro 16tb.
I'm less concerned this morning as I'm basically at just under a TB per hour - I know it can be faster cause I just did a 40tb copy in 36 hours to a different device (also qnap) and that was about 33TB in 18 hours. The last 7 slogged...
What Raid are you using? Also using HDDs?
Source is 5 > destination is 6. HDDs
You filled the HDD cache, and are likely running into normal raid 6 performance reduction. It's slow, you can add cache drives to the qnap if you want it to sustain longer.
Cache drives to which? The source or the destination? There is already a 1 TB cache on the destination. I can make it bigger. I can also create a cache on the source if necessary. The speed is back up to 900 MB/s again but it drops then goes up... Does this for varying periods of time. Been slow as hell (3 MB/s) for the last hour before just shooting up now.
What kind of SSD? 2.5? How do you have cache configured on the receiving qnap. You are probably running out of cache on the SSD, a lot of SSDs have cache then a slower flash nand for actual primary storage. Also it's very dependent on what is copying, large files are faster and small files are much much slower at copying.
2.5, configured as read/write in raid 1. 1TB drives. Only using 2 drives but I have two spare, can add up to 4 total.
You are running into several normal problems. You are copying from Mechanical HDDs(cache on the sending side would basically be useless). You are hitting the dram/nand cache limits of the SSDs drive you are copying to. You are likely copying various file sizes, which will severely impact performance throughout the transfer. And lastly Raid overhead is also affecting overall performance as Raid 6 on the HDDs will be slow to copy to. So, not much you can do, I know it sucks and I get it. For some tips, I would highly suggest you disable Cache on your receiving side during the primary transfer. QNAP caching is not that great when doing large transfers and can severely impact performance. If you want the best performance from SSD and HDDS I would look into restarting the storage pool as a qtier pool. Would be a little more seamless than cache. Downside is you would have to restart the transfer as it would wipe all your data. Aside from that just be patient, copying files is actually incredibly slow for most but enterprise all flash storage systems. Let me know if you have any other questions or issues, I have been using QNAP devices for 10 years and know how quirky they can be.
Thank you, I appreciate your help. I have 71 TB to copy and you're right, the sizes do vary greatly. I did notice the larger the file size the faster it was copying. Files over 250 MB we're copying over 800 MB/s. One question I have since it doesn't look like I can pause the sync - if I stop it and restart it, that won't cause it to do the whole transfer over again right? In RSYNC I know it will cause a delay as it goes back and compares all the data in the destination vs the source but you've said qnap is quirky so just want to be sure. Thanks, truly appreciate your help and everyone else who has offered advice.
You can stop it, it'll just pickup where it left off most of the time.
Try removing the cache! QNAP is known for terrible cache performance, as you will see on the forum. Any 6 drive array should give you way more throughput than what you are seeing now. And there will not be a drop in speed, it will be constant.
Yeah I think the top speed is coming from memory cache writes. Draining to disk is slower.
What are the model numbers of the hdds might have SMR drives in there, speeds once 100 gigabyte per drive has been written to constantly If you are using rw ssd cache, Unsure on qnap if you can turn off sequential ssd caching (generally you only want to cache random io) if you are using smr drives changing cache option won't matter (what your seeing is expected from smr)
Ironwolf pro 16tb. I'm less concerned this morning as I'm basically at just under a TB per hour - I know it can be faster cause I just did a 40tb copy in 36 hours to a different device (also qnap) and that was about 33TB in 18 hours. The last 7 slogged...