EX4100 Read speeds down to 300KB/s or lower

Hello, I have been happily using the EX4100 for a few years as a server for media and a file store. Recently, and unrelated to any change I can work out, movies won’t play and have been stuttering at best. The tests I’ve carried out show this is related to a huge, huge slowdown in read speeds from the array.

I have a 16port gigabit switch (unmanaged but I’ve tested cables and ports and computer<>computer is fine and all ports reporting gigabit connections - cable changes didn’t make any difference)

I have both Mac’s (wired), PC’s (wired) and laptops/ipads/phones all connected to the network and all other transfers are fine.

I found enabling Jumbo packets hugely improved the situation but screwed everything else up (too many devices I can’t configure with Jumbo packets - I tried 4000 & 9000 - 4000 was best as I think the ports on the switch have pretty small buffers). I’ve had to go back to normal MTU’s

Firmware reported as 2.31.193
All drives reporting healthy & fan speed good. No SMART errors.
I have 4*WD Red 6TB drives installed in a RAID 5 config with c17.91TB usable. All are the same model (WDC WD60EFRX-68L0BN1) and all arena the same firmware (82.00A82)

The array is relatively full now with 4.34TB free

If I try to copy a 4GB file to the desktop on my iMac - ETA for completion is 2 days
If I do the same on the PC - it reports a transfer speed of c300KB/s - crazy slow for a gigabit connection

I can WRITE to then as really quickly - around 110MB/s - quicker still with Jumbo frames enabled.

Has anybody got any additional diagnostic ideas or solutions. The Jumbo frame thing makes me wonder if the NAS firmware has screwed things up at some point as physically, everything seems to be fine - which the write speeds and jumbo frame speeds prove… this only happens on standard MTU’s)

Many thanks

Hi whaleyp,

You can refer to the link mentioned below in order resolve the issue.


Thanks… that’s all pretty basic stuff and although comprehensive, doesn’t help with my issue I’m afraid.