I’m using Linux Mint 17.3 KDE x64 and connecting to a WD My Cloud EX4100 vía a TP-LINK Archer C7 router by way of Ethernet. The NAS has 4 x 4TB drives configured in RAID 5, on top of which is an 11.7 TB iSCSI share formatted as ext4. All the drive tests that the EX4100 can do come up good, and SMART data indicates the drives are in perfect condition. I’m connecting using Open iSCSI, as it gives vastly faster speeds than anything else I’ve tried.
I’ve been transferring mostly large video files (~2 GB each) to the EX4100 using rsync, and I’ve discovered that they’re being corrupted. Perhaps one in every five videos is completely unplayable (and not even recognized as a video file by mediainfo), and the others have more subtle corruption. I say that because when I use the --checksum option with rsync after an initial copy-over, virtually everything gets transferred again, meaning that the source and copied files are not identical.
This is quite simply terrifying. If I hadn’t realized this now, who knows how much data I would have lost. I’m storing raw MTS video files from video cameras on the NAS (among other things, of course) and transcoding them to MP4 for actual use. I want to keep the MTS files around for when there are better codecs than MP4, or for editing, and so on --future-proofing, essentially-- but the only copy of these HUGE files was going to be on the NAS.
What could be going wrong here? Keep in mind this isn’t the odd flipped bit, so we can’t put it down to cosmic rays. This is vast corruption, and I have NEVER seen anything like it.