How to avoid that mount -o remount modifies on-disk data?
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I have an encrypted file system on a disk image file (using cryptsetup). The daily backup copies the disk image to the backup medium with rsync. Since this copies the entire image file when it was changed, it takes away a good chunk of backup space. I would like to avoid that if no changes were made to the data.
Before the image is copied to the backup, I have to mount -o remount,ro /diskimage (remount read-only) because otherwise the disk image on the backup contains a corrupted file system. After the backup, I make it writable again with mount -o remount,rw /diskimage
The problem is that one or both of the mount operations modify the disk image, even if the files in the file system were not changed at all. (I guess it is about a timestamp.) As a consequence, the image is always copied to the backup. Are there any mount options that avoid that the disk image is modified by a mount -o remount operation?
The file system is ext4 with options loop,noatime,acl,user_xattr,nofail,noauto.
backup mount disk-image ext4 read-only
asked Dec 4 at 8:57
j6t
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I have an encrypted file system on a disk image file (using cryptsetup). The daily backup copies the disk image to the backup medium with rsync. Since this copies the entire image file when it was changed, it takes away a good chunk of backup space. I would like to avoid that if no changes were made to the data.
Before the image is copied to the backup, I have to mount -o remount,ro /diskimage (remount read-only) because otherwise the disk image on the backup contains a corrupted file system. After the backup, I make it writable again with mount -o remount,rw /diskimage
The problem is that one or both of the mount operations modify the disk image, even if the files in the file system were not changed at all. (I guess it is about a timestamp.) As a consequence, the image is always copied to the backup. Are there any mount options that avoid that the disk image is modified by a mount -o remount operation?
The file system is ext4 with options loop,noatime,acl,user_xattr,nofail,noauto.
backup mount disk-image ext4 read-only
asked Dec 4 at 8:57
j6t
1011
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I have an encrypted file system on a disk image file (using cryptsetup). The daily backup copies the disk image to the backup medium with rsync. Since this copies the entire image file when it was changed, it takes away a good chunk of backup space. I would like to avoid that if no changes were made to the data.
Before the image is copied to the backup, I have to mount -o remount,ro /diskimage (remount read-only) because otherwise the disk image on the backup contains a corrupted file system. After the backup, I make it writable again with mount -o remount,rw /diskimage
The problem is that one or both of the mount operations modify the disk image, even if the files in the file system were not changed at all. (I guess it is about a timestamp.) As a consequence, the image is always copied to the backup. Are there any mount options that avoid that the disk image is modified by a mount -o remount operation?
The file system is ext4 with options loop,noatime,acl,user_xattr,nofail,noauto.
backup mount disk-image ext4 read-only
asked Dec 4 at 8:57
j6t
1011
I have an encrypted file system on a disk image file (using cryptsetup). The daily backup copies the disk image to the backup medium with rsync. Since this copies the entire image file when it was changed, it takes away a good chunk of backup space. I would like to avoid that if no changes were made to the data.
Before the image is copied to the backup, I have to mount -o remount,ro /diskimage (remount read-only) because otherwise the disk image on the backup contains a corrupted file system. After the backup, I make it writable again with mount -o remount,rw /diskimage
The problem is that one or both of the mount operations modify the disk image, even if the files in the file system were not changed at all. (I guess it is about a timestamp.) As a consequence, the image is always copied to the backup. Are there any mount options that avoid that the disk image is modified by a mount -o remount operation?
The file system is ext4 with options loop,noatime,acl,user_xattr,nofail,noauto.
backup mount disk-image ext4 read-only
backup mount disk-image ext4 read-only
asked Dec 4 at 8:57
j6t
1011
asked Dec 4 at 8:57
j6t
1011
asked Dec 4 at 8:57
j6t
1011
asked Dec 4 at 8:57
j6t
1011
asked Dec 4 at 8:57
j6t
1011
1011
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add a comment |
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