Negative effects when disabling journaling?

The Journal makes sure that when a file system is not properly dismounted, that all the file system structural data (metadata) is correct. Not properly dismounted could be an operating system crash, a power failure, the cable removed from the drive or computer accidentally, etc...

If the file system is not journalled, then the operating system must perform a full file system check (fsck) on the drive to make sure that the structure of the file system is intact and safe. For example, you need to make sure that no 2 files think they own the same disk sector, that all disk sectors are accounted for either as part of a file or as free storage, that all files can be found via a directory entry, etc...

File system checks can take a long time if there are a huge number of files on the file system. These days with terabyte sized disk drives, very often there ARE a huge number of files on a file system, so most file systems these days are journalled as the journal can be replayed to make sure that last set of file system structural changes were correctly applied, and that file system check does not need to be performed. Replaying the journal is quick.

NOTE: The journal does not contain any user data, just file system structural data. An improperly dismounted file system may loose user data for the files that are currently being modified.

So the risk is that if the file system is not dismounted properly, that a lenghtly file system check may be needed. A Time Machine backup tends to be very complex so expect a file system check that may take hours.

I see. So if I eject the drive correctly each time I should be fine, right?

Yes.

You will find out if the Mac re-mounts the file system quickly, or if it takes a few hours before it mounts. If it takes a few hours, then use Activity Monitor to look for a process with 'fsck' in the name, or use the ps command.

I'm surprised to hear tat you are having problems with the pi and disks formatted with journal on. Could you post the URL where you found this information all the sites I have seen don't seem to indicate a problem.

Keep in mid that if you what to change the format of the drive any data on that drive will be lost. So make sure you backup anything that you want to keep before re-formatting the drive.

regards

Do not use a Time Machine volume for anything other than Time Machine. Time Machine is for backups, not archives. It will delete data eventually. If you are taking part of the Time Machine volume for your own files, then Time Machine is going to fail eventually. The only solution will be to erase the volume, but you can't do that because you have other files there.

Do not mess with the internals of Time Machine. Do not take chances with your backup data. When there is a problem, you will be back up at point #1.

Do not connect a foreign device to Time Machine. If they can't handle journaling, then they probably can't handle the even more funky things that Time Machine is doing.

If you manage to corrupt your Time Machine volume and you share that volume with your own data, you stand a good chance of corrupting both your backups and your archive data, losing both.

What better ways are there to connect a Raspberry Pi to a Mac? All of them.

DO NOT touch your backup volume with anything but Time Machine. DO NOT disable journaling.

Jakelong wrote:

I've been using the same drive for backups and storage for the last 3 years without any problems.

I'm happy for you. But if you don't understand that something can 'work' and still be a bad idea, then... Well, when you do figure it out it will be the hard way, and there won't be a darned thing any of us can do to help you unravel the mess. Apologies in advance.

Incidentally, you may not need to buy a separate drive. If your current backup drive is large enough, partition it into two or more volumes and reserve one volume for TM.

Which model? The b has an ethernet port.

Network your mac & the PI.

Mac OS has NFS -- Network file system and Samba -- windows networking

You may need NFS Manager.app to configure NFS on your mac.

Robert

But what does that have to do with the missing write permission?

[A] You still thinking of writing to your backup disk? That's crazy man. No way you want to risk messing up your backup data. You have anything important backed up?

[B] Because you can share you folders on your mac over wifi to you Linux board. Hence you do not need to write to you backup disk.

[C] Get a 16gig flash drive $12 on sale & use this to share data between systems.

[D] Do you have an Intel mac? Get the free Oracle Virtual Box and run linux all you want in it.

You asked about the negative effects of turning off journaling, and, by extension, doing a laundry list of inadvisable things with your Time Machine data. I think you have been suitably informed of any potential negative effects.

By far, the biggest reason for not storing your own data on your Time Machine volume is that it results in exactly the scenario you describe. You want to use your data for something other than Time Machine. But because you have mixed them, that isn't possible. You can't reparition your Time Machine volume because you would now lose your archived data. So, you will put your Time Machine data at risk so that you can access the other data the way you want.

I must point out a flaw in your logic. A backup is there in case something goes wrong. It serves as peace of mind. In a best-case scenario, you will never use it. But, according to your logic, if you haven't experienced any unfavourable events, then there is no need to worry about the possibility of them happening. If that is true, why are you bothering with Time Machine at all? You haven't had any problems so far. As any gambling addict will tell you, past activity is a reliable indication of future performance.

I don't know what else we can tell you. You said "I really don't wanna mess up with the backups", but obviously you plan to do exactly that. Your backup drive is already 3 years old. You haven't said what kind of drive it is. 2.5" notebook drives tend to die after three years. My advice would be to get a newer, bigger backup drive and dedicate it to Time Machine or at least partition it for both Time Machine and archives. I also suggest encrypting it, which would never be Linux-compatible. Then you can dedicate your old drive to the Rasperry Pi, your backups will be safe, and everyone will be happy.