How to solve the IO error when importing the pool

IO error occurred while importing pool “NAS”
NAS pool is in FAULTED state. How to solve it?

错误: concurrent.futures.process.RemoteTraceback:
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/middlewared/plugins/zfs
/", line 227, in import_pool
zfs.import_pool(found, pool_name, properties, missing_log=missing_log, any_host=any_host)
File “libzfs.pyx”, line 1369, in libzfs.ZFS.import_pool
File “libzfs.pyx”, line 1397, in libzfs.ZFS.__import_pool
libzfs.ZFSException: cannot import ‘NAS’ as ‘NAS’: I/O error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “/usr/lib/python3.11/concurrent/futures/”, line 256, in _process_worker
r = call_item.fn(*call_item.args, **call_item.kwargs)
File “/usr/lib/python3/dist-packages/middlewared/”, line 112, in main_worker
res = MIDDLEWARE._run(*call_args)
File “/usr/lib/python3/dist-packages/middlewared/”, line 46, in _run
return self._call(name, serviceobj, methodobj, args, job=job)
File “/usr/lib/python3/dist-packages/middlewared/”, line 34, in call
with Client(f’ws+unix://{MIDDLEWARE_RUN_DIR}/middlewared-internal.sock’, py_exceptions=True) as c:
File “/usr/lib/python3/dist-packages/middlewared/”, line 40, in call
return methodobj(*params)
File “/usr/lib/python3/dist-packages/middlewared/schema/”, line 191, in nf
return func(*args, **kwargs)
File "/usr/lib/python3/dist-packages/middlewared/plugins/zfs
/", line 207, in import_pool
with libzfs.ZFS() as zfs:
File “libzfs.pyx”, line 529, in libzfs.ZFS.exit
File "/usr/lib/python3/dist-packages/middlewared/plugins/zfs
/", line 231, in import_pool
raise CallError(f’Failed to import {pool_name!r} pool: {e}', e.code)
middlewared.service_exception.CallError: [EZFS_IO] Failed to import ‘NAS’ pool: cannot import ‘NAS’ as ‘NAS’: I/O error

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File “/usr/lib/python3/dist-packages/middlewared/”, line 469, in run
await self.future
File “/usr/lib/python3/dist-packages/middlewared/”, line 511, in _run_body
rv = await self.method(*args)
File “/usr/lib/python3/dist-packages/middlewared/schema/”, line 187, in nf
return await func(*args, **kwargs)
File “/usr/lib/python3/dist-packages/middlewared/schema/”, line 47, in nf
res = await f(*args, **kwargs)
File "/usr/lib/python3/dist-packages/middlewared/plugins/pool
/", line 113, in import_pool
await‘zfs.pool.import_pool’, guid, opts, any_host, use_cachefile, new_name)
File “/usr/lib/python3/dist-packages/middlewared/”, line 1564, in call
return await self._call(
File “/usr/lib/python3/dist-packages/middlewared/”, line 1425, in _call
return await self._call_worker(name, *prepared_call.args)
File “/usr/lib/python3/dist-packages/middlewared/”, line 1431, in _call_worker
return await self.run_in_proc(main_worker, name, args, job)
File “/usr/lib/python3/dist-packages/middlewared/”, line 1337, in run_in_proc
return await self.run_in_executor(self.__procpool, method, *args, **kwargs)
File “/usr/lib/python3/dist-packages/middlewared/”, line 1321, in run_in_executor
return await loop.run_in_executor(pool, functools.partial(method, *args, **kwargs))
middlewared.service_exception.CallError: [EZFS_IO] Failed to import ‘NAS’ pool: cannot import ‘NAS’ as ‘NAS’: I/O error


Did you import and access this pool from multiple systems at the same time?
For example, from two VMs or a host and a VM.

1 Like

I have reinstalled the system, but now I cannot roll back to the previous system. Is there any solution?

root@truenas[~]# zpool import 7203497266836193727
cannot import 'NAS': pool was previously in use from another system.
Last accessed by truenas (hostid=42a93b67) at Mon May 20 23:55:16 2024
The pool can be imported, use 'zpool import -f' to import the pool.

“The pool can be imported, use zpool import -f to import the pool”

It still shows IO errors

root@truenas[~]# zpool import -f NAS
cannot import 'NAS': I/O error
        Destroy and re-create the pool from
        a backup source.

Is this bare metal or virtualized?

physical machine

However you ended up in this situation, this thread in the old forums has a person seeing a similar error recover most data:

Specifically note post #17 and the use of the non-destructive -n flag for a test run before going without that flag.

If it eventually imports, export and then reimport using the GUI.

# zpool import -f -FXn PoolName

This doesn’t seem to work for me

# zpool import -f -FX NASNAS
camnot import "NAS': one or more devices is currently unavailable