We use the QNAP TS-112 was a server for our business and have an external USB drive running in real time synchronisation as a backup. I swap the external drive regularly and keep the disconnected drive off site.

I run two synchronising jobs, one for each of the two external drives that I use. When I swap the drive I stop the job, then eject the drive and reconnect the other drive and restart the job for the drive.

Recently I've been having problems when I reconnect an external drive. The synchronising starts then either hangs or starts giving errors.  This will happen with both drives.  The only way I've been able to fix the problem is to reformat the drives and start again.

Normally I can read the drives by plugging them into my laptop. Since this problem has been happening I've had problems doing that.  Running CHKDSK and repairing errors fixes that problem.

I'm suspicious that my problem is caused when I eject the drives. Even after I've ejected the drives, and the QNAP interface on the laptop shows the drive is ejected, the LED on the drive is still lit and you can hear the drive still spinning.  This makes me think the drive isn't being ejected properly and may be the cause of my problems.

This issue seemed happen after a firmware update, though I'm not sure about that. I did update to a later firmware but this made no difference.

At the moment the only way I can see to get around the problem is to shut the NAS down after ejecting the drive and restarting after I've reconnected the other drive. I've yet to try this to see if it works but it seems a long winded way of doing things.

Any ideas on what the problem might be and any fixes?

Thanks