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Very slow reads from DSM on new hardware. Writes are fine.





I recently updated both hardware and software from my home NAS. I went from an Asrock J-5005 ITX with DSM6 (jun's loader) to a new Asrock N100DC-ITX with DSM7.2 (i18n's arpl, using 918+ image to avoid messing with devicetree stuff). Migration went perfectly and with no issues.


However... my read speeds are quite low. They were not spectacular before but I think they have gone lower. I have a RAID5 consisting of 3 WD RED 8TB and Intel X-540-T2 as NIC. The volume gives around 300MiB/s in both sequential read/write when tested locally with dd (in order: sequential read speed test, sequential write speed test, cpu basic test):



Iperf shows correct speeds (bottleneck here is the NIC from the computer acting as client, so 2.5Gb is fine)



But when I try to copy a big video file from the NAS to my computer via SMB (tried forcing SMB3, no changes) the speed is all over the place, with an average speed of about 70MiB/s, and lots of peaks and valleys from 40 to 100-ish. I am the only user and there is almost no background apps.



If i copy the exact same big file from the computer to the NAS, this happens (what I expected for both situations since this is mostly sequential):



Jumbo frames are enabled on both sides, MTU is set at 9000. The NIC on my computer is only 2.5GbE, but that should not be relevant for this case (the switch, a netgear SX-10, shows the correct speeds for both clients)


Since the motherboard has only two SATA ports, I am using a JMB585 SATA controller (like this one:; https://es.aliexpress.com/item/1005005560439951.html ) for the third one, but as I said local dd speeds look fine. I tried moving all the disks to this controller (first results were with 2 on the onboard controller + 1 in the JMB585) and made no difference.


Any idea of what am I missing?


Thanks in advance.


Edited by Pollonidas
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