I am trying to use rsync to sync files from my laptop (Ubuntu 14.04) to an external disk. When connecting the disk I start the sync with the following command:

rsync -av --delete /home/alexander/10_Private /media/alexander/LACIESHARE/Backup

It starts fine, but later on every transfer faild because I do not have write permission on the disk any more; here part of the output of the rysnc command:

rsync: mkstemp "/media/alexander/LACIESHARE/Backup/10_Private/Swiss/.Oeffnungszeiten.pdf.pKmrxs" failed: Read-only file system (30)
rsync: mkstemp "/media/alexander/LACIESHARE/Backup/10_Private/Swiss/COOP/.Adressaenderung.pdf.zCxEJn" failed: Read-only file system (30)

How is it possible that rsync suddenly changes the file-system of the external disk to 'read-only'? What is going on, and how to fix this behaviour?

During the sync, I have nothing done regarding the external disk; no other file copy, file access...


The drive is probably mounted with the errors=remount-ro option, AND there are read or write errors while running the rsync. That option causes the drive to be remounted as read-only if there are any read or write errors detected.

This could be caused by a bad connector or cable, bad port (e.g. USB or esata), or because the drive itself is failing.

In other words, it's probably a hardware fault.

  • This makes sense, but I cannot see this mounting option: /dev/sdc1 on /media/alexander/LACIESHARE type vfat (rw,nosuid,nodev,uid=1000,gid=1000,shortname=mixed,dmask=0077,utf8=1,showexec,flush,uhelper=udisks2) – Alex Oct 28 '15 at 10:10
  • 1
    errors=remount-ro is the default for FAT filesystems. man mount, search for FAT.*error – cas Oct 28 '15 at 10:13

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