I reformatted and installed Panther on my eMac with Journaling Enabled (by default) and then disabled it to see if I could notice any speed improvements. Who out there has Journaling Enabled with Panther? Is it really a good thing to have on?
I have it installed but don't know what it is doing. Also don't know what the Restore feature is in the Disk Utility when you boot from the Panther Install CD?
It minimizes the chance of disk corruption, and when you hard reset the machine, makes boot times faster.
Some people believe that it slows down their machine. Wellll.... not really, for most people. It does provide a small amount of overhead to any time you write data to the disk, but not when you read it. And, that overhead is about 5-8% of a speed hit to the write, which isn't bad at all for what you get.
-------- Techy explanation ---------
Normally when the OS requests that a bit of data be written, it's a hands off approach - the OS simply trusts that it will be done, and doesn't check. Many such requests can be queued up since the disk is slower than the OS, and if the system goes down, those requests may never be completed. Unfortunately, the system thinks they were, so your OS's view of the drive and what's actually there may not be in sync - this way lies madness. The journal makes a note of every request, and when it's completed, that entry is removed. Essentially the journal is just a 'to do' list for the disk.
Additionally, if the system is taken down improperly, that queue of requests may not get performed (flushed is the technical term), which is done at shutdown. The final thing that happens at shutdown is that the drive is marked as 'clean'. On boot, if that clean flag isn't set, the system has to check the disk... this can be a lengthy process (several minutes) for a large drive. Journaling allows the OS to *only* have to check the items still in the journal, which is much, much faster.
I have yet to find any real solid real-world reason *not* to enable journaling, but some folks swear there is. (I can see possibly not doing it for real-time video streaming to disk, but luckily you can shut it on/off on a per-drive basis, so your system can be optimized selectively.)
I had to turn journaling off because VPC (version 5, at least) was excruciatingly slow with it enabled.
After upgrading to Panther, I needed to use VPC. I started the Win2K boot and about a half hour later it still hadn't finished booting. So, needing to get something done in 2K, I rebooted the machine to OS 9 and went from there. Luckily, that same day I needed to run fsck on the disk and was informed that journaling was enabled. I hadn't realized that the Panther install automatically turned on journaling. I had a thought that perhaps the two things (super-slow VPC 5 and journaling) were related, so I turned off journaling. Yup.
Comments
The safest way to do that would probably be
1) archive and install
2) make an image (CCC or some such)
3) reformat/clean install
4) image the new, JFS'd HD
right?
Originally posted by machem
Journaling would require a clean install, also, eh?
The safest way to do that would probably be
1) archive and install
2) make an image (CCC or some such)
3) reformat/clean install
4) image the new, JFS'd HD
right?
There's an option to enable journaling in Disk Utilities, and it makes no mention of clean installs.
I see no reasons to not have it turned on, at least not on my machine (dual gig G4).
Originally posted by Whisper
There's an option to enable journaling in Disk Utilities, and it makes no mention of clean installs.
So that's where it is. Thank you. (I found out I have it turned on.)
Some people believe that it slows down their machine. Wellll.... not really, for most people. It does provide a small amount of overhead to any time you write data to the disk, but not when you read it. And, that overhead is about 5-8% of a speed hit to the write, which isn't bad at all for what you get.
-------- Techy explanation ---------
Normally when the OS requests that a bit of data be written, it's a hands off approach - the OS simply trusts that it will be done, and doesn't check. Many such requests can be queued up since the disk is slower than the OS, and if the system goes down, those requests may never be completed. Unfortunately, the system thinks they were, so your OS's view of the drive and what's actually there may not be in sync - this way lies madness. The journal makes a note of every request, and when it's completed, that entry is removed. Essentially the journal is just a 'to do' list for the disk.
Additionally, if the system is taken down improperly, that queue of requests may not get performed (flushed is the technical term), which is done at shutdown. The final thing that happens at shutdown is that the drive is marked as 'clean'. On boot, if that clean flag isn't set, the system has to check the disk... this can be a lengthy process (several minutes) for a large drive. Journaling allows the OS to *only* have to check the items still in the journal, which is much, much faster.
I have yet to find any real solid real-world reason *not* to enable journaling, but some folks swear there is. (I can see possibly not doing it for real-time video streaming to disk, but luckily you can shut it on/off on a per-drive basis, so your system can be optimized selectively.)
I noticed now that the fsck -y mode doesn't work the same with journaling. You have to add -f to the end of it. I think the new fsck would be
fsck -y -f
Is fsck even necessary any more?
Originally posted by kcmac
It is installed in the on position by default. I did a simple upgrade.
I noticed now that the fsck -y mode doesn't work the same with journaling. You have to add -f to the end of it. I think the new fsck would be
fsck -y -f
Is fsck even necessary any more?
OT: KC here too, OP actually.
Get Info on your boot disk. It should either say Mac OS Extended or Mac OS Extended (Journaled) next to Format.
After upgrading to Panther, I needed to use VPC. I started the Win2K boot and about a half hour later it still hadn't finished booting. So, needing to get something done in 2K, I rebooted the machine to OS 9 and went from there. Luckily, that same day I needed to run fsck on the disk and was informed that journaling was enabled. I hadn't realized that the Panther install automatically turned on journaling. I had a thought that perhaps the two things (super-slow VPC 5 and journaling) were related, so I turned off journaling. Yup.