Some times, you might get errors in your sinology and be unable to delete files. This is likely due to a corrupted filesystem which requires fixing.
i found the instructions to do it here.
For good measure (reference) i have replicated the part that i felt is the most important here.
The Procedure
Make sure you have read the background info above so you understand the nameing convention used below. Single bay NAS users replace /dev/… as neccessary
- Ensure you have a backup of your data
- Reboot your NAS
- Enable the Command Line Interface (Telnet or SSH)
- Install and use smartmontools as described in A short list of the more useful 900+ ipkg packages to do a “long self test” on each drive in your NAS.
- After using smartmontools login to the command line as root
- Type “df” to see what is mounted on your NAS.
- Before you unmount the desired partition, stop services running on the NAS, using the following commands: “/usr/syno/etc/rc.d/S25download.sh stop”, “/usr/syno/etc/rc.d/S20pgsql.sh stop”, “/usr/syno/etc/rc.d/S80Samba.sh stop”. If you don’t do this, you may get an error when you run the volume check, “Device or resource busy while trying to open /dev/md2”.
- Now you must unmount anything that is directly or indirectly mounted to the partition you want to check. For example let’s check /volume1. Everyone should have /dev/md2 mounted as /volume1. To unmount it use the command “umount -f /volume1”. Some of you may also see that subdirectories of /volume1 are mounted, e.g. you may see /volume1/opt mounted as /opt in which case you will also need to “umount -f /opt” etc.
- First we will do a read only “logical” check on the /volume1 data (i.e. partition /dev/md2), enter the command “e2fsck -v -n -f /dev/md2” this check may take from 10 minutes to 2 hours depending on how much data you have and how many errors are found.
- If you have any other partitions, e.g. /volume2 then you can check those by unmounting it and using the command “e2fsck -v -n -f /dev/md3” etc.
- For partitions that have errors you should re-run the e2fsck command in the “make changes mode” e.g. use the command “e2fsck -v -f -y /dev/md2”.
- It would be nice if we could also check the Operating System partition /dev/md0, however, I do not know a way to unmount it and leave the NAS operational. You could use e2fsck in the check only mode e.g. “e2fsck -v -n -f /dev/md0” with the partition still mounted, but I warn against doing this as it may report errors that don’t really exist.
- When you have finished repairing any “logical” errors reboot the NAS, e.g. enter the command “reboot”.