So its been a while since ive been able to progress this, but it seems leaving it alone helped.
In response to DrKK -
I had the same thoughts as you, why couldnt i just put a new drive in. I tried, but none of the zpool commands would work because the pool was not mounted (it was online)
I got called away on aproject, and just left it sitting for 10 days.
When i got back and looked at it, i started seeing some issues with filenames of data stored in the pool - thats strange i thought.
All of a sudden the pool was back online - just needed time to 'mount' i guess.
So after that i popped in a new 2tb drive and selected to replace it, this is where my current woes are.
The drive is continually resilvering. It never completes. (the failed drive is still installed, and im not sure if i should remove it)
Every time i look at the output from zpool status, it shows that the resilver has started at a different time.
I have been able to recover the core of the data off this system that i wanted to.
Should i just remove the troublesome drive now and see what happens?
pool: storage
state: ONLINE
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scan: resilver in progress since Wed Aug 19 13:33:49 2015
13.3T scanned out of 32.7T at 528M/s, 10h44m to go
23.5G resilvered, 40.49% done
config:
NAME STATE READ WRITE CKSUM
storage ONLINE 1.24K 0 0
raidz2-0 ONLINE 0 0 0
gptid/5213272e-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/527a014f-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/52ddec11-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/534088df-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/53a57b8e-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/54104636-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/54755fcc-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/a7552ce7-8a7a-11e4-a46f-00259065cebd ONLINE 0 0 0 block size: 512B configured, 4096B native
gptid/5541205d-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/5196311c-e8b0-11e3-ba3e-00259065cebd ONLINE 0 0 0 block size: 512B configured, 4096B native
gptid/56102462-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
gptid/5675e4b4-39f8-11e1-bb85-00259065cebc ONLINE 0 0 0
raidz1-1 ONLINE 0 0 0
gptid/de789459-a395-11e4-8adf-00259065cebd ONLINE 0 0 0
gptid/c614533f-df38-11e3-815f-00259065cebd ONLINE 0 0 0
gptid/55ebee3a-9617-11e3-8fb0-00259065cebd ONLINE 0 0 0
gptid/586e26a9-9617-11e3-8fb0-00259065cebd ONLINE 0 0 0
gptid/76e94bcd-e025-11e3-8b40-00259065cebd ONLINE 0 0 0
gptid/775ae1ae-e025-11e3-8b40-00259065cebd ONLINE 0 0 0
replacing-4 ONLINE 1.24K 0 0
gptid/671798f4-2572-11e5-afa2-00259065cebd ONLINE 1.24K 0 5 (resilvering)
gptid/64c2b9d4-40ce-11e5-8cb6-00259065cebd ONLINE 0 0 2.48K (resilvering)