I'm using Ubuntu 14.04 LTS server edition as a home server, and i created a raid0 array from my two old 298 GB external HDD-s. After some time, when tried to copy some files i run into the error: 'Error copying files: Read-only filesystem. And because i was unable to umount the array i just rebooted the computer. However the startup has stuck at mounting the array, so i selected to fix it manually but when i tried to mount the array, it failed bicase 'the device is not ready', so i started e2fsck, but it failed at 99% with the message: I/O device error or something like this (i can't remember the exact message).
I thought that maybe one of the drives had died, so i shutted down the computer and connected the drives to my laptop to check them with DiskInternals' Linux Reader under win8.1. The program saw the array and could access and save it's content to somewhere else.
Rebooted the laptop to boot into Deepin 15.2 and started the repair process (assembled the array and then started e2fsck). Result: everything's fine with it. Mounted it and an r/w test (copied some random files to some random directories on it) indicated the same: everything's OK. When the server started up again, an e2fsck had run, but this time without errors. I rebooted it 3 times and it rebooted 3 time without any error, so i put it back to it's place.
After that, the I/O error never happened again, but the read-only fs did. A reboot solves it, but I'd like to know why is this happening and how to fix it permanently (if possible). The array contains a Samsung S2 Portable USB 2.0 external hdd and a 2,5" Samsung HN-M320MBB hdd in a usb 2.0 enclosure.
sorry for the grammar, i'm not native english