Disk Utility - Enable journaling??

[Andrew Hogan]

Hi all,

I've just added a third internal HDD to my good old DP G4 800.
In Disk Utility you get the option of setting it as Mac OS Extended or Mac OS Extended (journaled). Whats the difference and should all HDDs be journaled or not. The original Startup HDD is journaled.

thanks

[Shane Ross]

Not exactly sure what the difference is, but DON'T JOURNAL the drive.

That is bad.

[Vic Owen]

Journaling helps protect the integrity of the extended file systems on OS-X volumes. It prevents the disk getting all screwed up and speeds up any repair work. The journal keeps a continous record of file changes on your HD. If you crash during a power failure or some other reason, the journal will assist in the recovery.

I disagree with the previous post -- I've had no problems with the Journaling feature turned-on.

[Ken Tanaka]

Journaling on disk drives is basically a technique to help minimize loss in the event of a sudden failure, such as a power outage. It's most useful on servers, less worthwhile on relatively low-write traffic drives. It -does- impose a degree of performance overhead.

I do not journal my secondary internal drive.

Apple has a good, concise explanation on their support site.

[Shane Ross]

But on the Apple FCP discussion sites...experts have said over and over and over NOT to have journaling on when you format the drive. Journaling might be fine for all other needs, but avoid it on your media drives.

Journaling and video media do not (seem to) mix well.

Do a search in this discussion group and you'll see:
http://discussions.info.apple.com/We...epP.0@.ee6bcd7

Also read this article on the subject:
http://www.kenstone.net/fcp_homepage...ournaling.html

[Vic Owen]

I can support these arguments -- I don't have journaling activated on my big media drive, but do on my boot and another internal drive.

[Rob Lohman]

I would not trust my precious data to a non journalling file system
personally. I'm on Windows (PC) myself and am using NTFS which
is a journalling filesystem. Yes, there is overhead, but it should
not have much impact on a 3.6 MB/s DV stream. Ofcourse I don't
know how everything holds up on a Mac, but in theory it should be
no problem at all.

The most often cause for a journalling system needing to fix the
system (which you will not notice) is a power outage.

The idea behind a journalling file system is that all destructive
actions taking place on a volume are being logged. So if you
would be struck by a power outage for example, the system will
know (when it comes back up) how to get the file system back
into a known state instead of a corrupt one.

Shane, from the article you linked to:

I'm a post-production consultant to a variety of broadcast and film production studios throughout Hollywood. In dealing with my clients, their number one concern is maximizing the performance of their equipment, while maintaining the highest level of data integrity.

That is quote logical since Hollywood is working with much, MUCH
higher datarates (1K, 2K sometimes 4K resolutions) and need
the most throughput they can get. Also their large arrays will
most likely offer some form of RAID with both striping and
mirroring or parity to provide for fast throughputs AND safety
against harddisk failure.

They are most likely protecting themselves from power failure with
high capacity batteries and diesel generators. I know we do at
the company I work for (which does webhosting among other things)

Again, we work with a small 3.6 MB/s DV stream which should
have more than enough extra bandwidth to do journalling (which
isn't that system demanding to do). Unless you have your system
behind a verified working UPS system, why take the chance?

I would even go as far as to say that it would make MORE sense
to switch it around (if you want only one drive with journalling, I
use journalling on all my drives and this only goes for OUR DV
world!): have it on our media drives but not on our OS drive.
Personally I would care much less if my OS becomes corrupt (and
would not boot) than my media and project files would be. It's
easy to reinstall my OS and get my NLE back up to finish a project
then it would be to reconstruct a project I've been working on
from scratch (ie, loosing your project files and perhaps other
media you generated or specific sections you captured!).

[Jeff Donald]

Use journaling for your boot drive, but DO Not use journalling for your media. This only applies to those using 10.3.x. Journalling is not an option for 10.2.x users.

[Rob Lohman]

Could you elaborate on that Jeff? Is this a Mac "thing"? I'm a bit
confused why everyone "seems" to be so against journalling for
a media drive on OS X.

[Jeff Donald]

This is a quote from Apple Support, Article 107249:

When Should Journaling Be Used?

Journaling is best suited for servers requiring high availability, servers containing volumes with many files, and servers containing data that is backed up at infrequent intervals (nightly, for example).

If a volume contains read-only data that is not mission-critical, it may not be necessary to turn on journaling if performance is more important than safety.

If your server contains high-bandwidth usage data files, such as large video, graphics, or audio files, you may want to weigh the benefits of using journaling against the performance needed to access your data. In most cases, the impact of journaling upon data access performance are unnoticeable to users, but its implementation may not be practical for servers where data access demands outweigh its benefits.

You have to look at the total bandwidth, such as multiple video and audio tracks and Real Time Effects. Data needs to be accessed much quicker than the 3.6MB/s DV stream. The risk to media files is minimal, while the performance hit can be significant, enough to cause stuttering or an occasional dropped frame. The risk to the System drive is greater and I recommend leaving journaling on.

[Rob Lohman]

Keep in mind that reading has no journalling overhead, so accessing
data should not be slower, so I'm really wondering if this is just
a fear or if it is really a factor for the kind of work we all do.

But I guess it is something we perhaps just disagree in, that's okay <g>

[Mark Sloan]

Originally, in OS 10.2.2 you could do a command line and turn journaling on with a 10-15% performance hit. The server version utilized more RAM to make the hit 2-3%. I haven't seen any tests to see the speed difference but I would guess it is in the 2-3% range by now.
"Like most current journaling filesystems, HFS+ only journals meta-data."
This means it can help you recover from an immeadiate failure because it is essentially making scratch space. This will help in a huge number of error problems because damage mostly happens to the part of the disk that is currently being written to. This will not help you if a disk sector goes bad over time or some other kind of disk failure. You should back up regularly or set up a RAID with 2 of your internal drives if you want real data integrity. It does help your directory structure from getting hosed and having to go through a long process of rebuilding your disk directory structure so that all of those 1s and 0s have ownership again.

For the performance hit it is probably worth it for the type of work you are doing. I personally do not enable it... but probably should remember to! I think you can turn it on at a later date with no problem though. Check it out and see.

[Jeff Donald]

Yes, you can turn journaling on and off when you want. I think it slows the first one or two reboots as it compiles data for later use. The ram usage can be critical for many users. If your system has 2GB of Ram your probably fine. But for people running FCP with 512MB the loss of ram for journaling could be enough to cause glitches in audio etc. Audio and RT effects can be very ram intensive.

[Andrew Hogan]

Thanks everyone, I'm glad I asked the question. I have only 768MB Ram on my G4 so I think I will turn journaling off on this new drive (for the moment anyway) we very rarely have power outages.

Cheers!