Why doesn’t BIT make an incremental backup?
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I created a ‘full’ backup against my most important folder tree – about 250 GiB, containing about 50K items. It took far longer than I expected, but did complete. I did not use checksum. I did specify that the folder tree was to be checked for changes every 12 minutes. I then made a single file change as a test – an important change to an important file. 4 hours later BIT had still not made an incremental backup, but rsync has been running, consuming about 1% of my reasonably fast CPU throughout that time. A simple running of FreeFileSync comparing the current folder tree with the full backup made 4 hours ago immediately shows the one file I changed, but BIT has not seen it – meaning that this change might be lost if I restore my ‘original’ folder tree now. This loss of data is not what I expected. Why does it happen? I also notice that BIT did not backup a file of type .kra~ (a Krita file). This too appears to be an example of data lost by BIT. Why did that happen?
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On Thu, 2023-11-30 at 22:26 +0000, LateJunction wrote:
I think at this point it is better to open a new issue https://github.com/bit-team/backintime/issues and provide us all information to make this reproducible, mainly: - the configuration (screen shots) - screen shot of the taken snapshots .kra~ files are not backed-up because there is a default exclusion list for temp files in the "exclude" tab of the configuration dialog: *~
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On 11/30/23 17:26, LateJunction wrote:
I created a ‘full’ backup against my most important folder tree – about 250 GiB, containing about 50K items. It took far longer than I expected, but did complete. I did not use checksum. I did specify that the folder tree was to be checked for changes every 12 minutes. I then made a single file change as a test – an important change to an important file. 4 hours later BIT had still not made an incremental backup, but rsync has been running, consuming about 1% of my reasonably fast CPU throughout that time. A simple running of FreeFileSync comparing the current folder tree with the full backup made 4 hours ago immediately shows the one file I changed, but BIT has not seen it – meaning that this change might be lost if I restore my ‘original’ folder tree now.
This loss of data is not what I expected. Why does it happen?
What file system type are you using on your host and backup medium files? You can reply with the output of the "df -T" command, which will show this information for all mounted file systems. Is your backup medium directly connected to your computer, or is it accessed via a network connection? To make use of the "hard link" features BIT expects, you must be using a file system that supports this feature. All native Linux file systems do, but non-native file systems may not. This could result in BIT copying all 250 GiB every time.
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Firstly, my apology for seeming to have ignored your helpful reply to my original post. This was not intentional: I had no idea that there had been any responses to any of my post to the mailing list, until earlier this morning,, because I can see no indication that replies have been made. Indeed I will say that I find this mailing list implementation to be difficult to use: even now the only way I can find the list of threads, and potential responses, is via the 'posting activity' of my account profile. There should be a simpler way. In the interim between your reply and this acknowledgement, I have concluded that the situation I reported has one explanation: operator ineptitude. Having deleted that profile and its associated snap shots, BIT is now delivering the results I expected. To answer your questions: 1. File system type: Ext4 on both host and backup medium, under Linux Mint 21.2 2. output of 'df -T' command: Filesystem Type 1K-blocks Used Available Use% Mounted on tmpfs tmpfs 3266288 2068 3264220 1% /run /dev/nvme0n1p2 ext4 155572568 17273612 130323484 12% / tmpfs tmpfs 16331428 8 16331420 1% /dev/shm tmpfs tmpfs 5120 4 5116 1% /run/lock /dev/nvme0n1p3 ext4 322826564 158398048 147956760 52% /media/tony/7D-xtra /dev/nvme0n1p1 vfat 94759 6186 88574 7% /boot/efi /dev/nvme1n1p2 ext4 921853660 284315764 590636548 33% /home /dev/sda1 ext4 960302096 371353232 540094440 41% /media/tony/7D-Backup tmpfs tmpfs 3266284 1708 3264576 1% /run/user/1000 3. Backup medium (HDD) is directly connected to my system (and is manually replicated, for resiliency, using FreeFileSync, to multiple USB connected HDDs) 4. I believe my system, as far as BIT use is concerned, supports hardlinks throughout.
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On Thu, 2023-11-30 at 22:26 +0000, LateJunction wrote:
I think at this point it is better to open a new issue https://github.com/bit-team/backintime/issues and provide us all information to make this reproducible, mainly: - the configuration (screen shots) - screen shot of the taken snapshots .kra~ files are not backed-up because there is a default exclusion list for temp files in the "exclude" tab of the configuration dialog: *~
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On 11/30/23 17:26, LateJunction wrote:
I created a ‘full’ backup against my most important folder tree – about 250 GiB, containing about 50K items. It took far longer than I expected, but did complete. I did not use checksum. I did specify that the folder tree was to be checked for changes every 12 minutes. I then made a single file change as a test – an important change to an important file. 4 hours later BIT had still not made an incremental backup, but rsync has been running, consuming about 1% of my reasonably fast CPU throughout that time. A simple running of FreeFileSync comparing the current folder tree with the full backup made 4 hours ago immediately shows the one file I changed, but BIT has not seen it – meaning that this change might be lost if I restore my ‘original’ folder tree now.
This loss of data is not what I expected. Why does it happen?
What file system type are you using on your host and backup medium files? You can reply with the output of the "df -T" command, which will show this information for all mounted file systems. Is your backup medium directly connected to your computer, or is it accessed via a network connection? To make use of the "hard link" features BIT expects, you must be using a file system that supports this feature. All native Linux file systems do, but non-native file systems may not. This could result in BIT copying all 250 GiB every time.
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Firstly, my apology for seeming to have ignored your helpful reply to my original post. This was not intentional: I had no idea that there had been any responses to any of my post to the mailing list, until earlier this morning,, because I can see no indication that replies have been made. Indeed I will say that I find this mailing list implementation to be difficult to use: even now the only way I can find the list of threads, and potential responses, is via the 'posting activity' of my account profile. There should be a simpler way. In the interim between your reply and this acknowledgement, I have concluded that the situation I reported has one explanation: operator ineptitude. Having deleted that profile and its associated snap shots, BIT is now delivering the results I expected. To answer your questions: 1. File system type: Ext4 on both host and backup medium, under Linux Mint 21.2 2. output of 'df -T' command: Filesystem Type 1K-blocks Used Available Use% Mounted on tmpfs tmpfs 3266288 2068 3264220 1% /run /dev/nvme0n1p2 ext4 155572568 17273612 130323484 12% / tmpfs tmpfs 16331428 8 16331420 1% /dev/shm tmpfs tmpfs 5120 4 5116 1% /run/lock /dev/nvme0n1p3 ext4 322826564 158398048 147956760 52% /media/tony/7D-xtra /dev/nvme0n1p1 vfat 94759 6186 88574 7% /boot/efi /dev/nvme1n1p2 ext4 921853660 284315764 590636548 33% /home /dev/sda1 ext4 960302096 371353232 540094440 41% /media/tony/7D-Backup tmpfs tmpfs 3266284 1708 3264576 1% /run/user/1000 3. Backup medium (HDD) is directly connected to my system (and is manually replicated, for resiliency, using FreeFileSync, to multiple USB connected HDDs) 4. I believe my system, as far as BIT use is concerned, supports hardlinks throughout.
participants (4)
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BiT dev
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LateJunction
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Reece R. Pollack
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Tony Hamilton