Journaling - any benefits for a MacBook?
in [Mac Systems]
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From: Mark Conrad on 30 May 2010 12:56 In article <1jjaylp.ttqbyr1nfj9okN%mikePOST(a)TOGROUPmacconsult.com>, Mike Rosenberg <mikePOST(a)TOGROUPmacconsult.com> wrote: > Mark Conrad <aeiou(a)mostly.invalid> wrote: > > > I have been leaving journaling turned off for ages > > on my MacBook Pro, with nothing bad happening. > > > > Is journaling just a placebo? > > A quick Google search led me right to this: > > http://support.apple.com/kb/ht2355 Yep, and that article stated: "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." In my case, performance is the main bottleneck, not any file system "inconsistency" that may happen every 3 years. The article in that website further states: "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." I consistently handle very large files, 100 GB and over, even though I do not run a server. I am not knocking journaling for servers, for them it is essential, to minimize down time. For the rest of us "hobby" users, I question whether the few percent "penalty" of running journaling is worth it, when most of us can use all the speed we can muster, instead of wasting our speed on journaling, which may or may not save a very few recent files once every 3 years. Mark-
From: JF Mezei on 30 May 2010 14:45 I can see where journalling affects write performance. But does journalling affect read performance ? Say you have periods of the day where you have alots of writes being done, and periods where you have lots of reads. Would journalling affect that period where you do mostly just reads ?
From: Doug Anderson on 30 May 2010 15:04 Mark Conrad <aeiou(a)mostly.invalid> writes: > In article <1jjaylp.ttqbyr1nfj9okN%mikePOST(a)TOGROUPmacconsult.com>, > Mike Rosenberg <mikePOST(a)TOGROUPmacconsult.com> wrote: > > > Mark Conrad <aeiou(a)mostly.invalid> wrote: > > > > > I have been leaving journaling turned off for ages > > > on my MacBook Pro, with nothing bad happening. > > > > > > Is journaling just a placebo? > > > > A quick Google search led me right to this: > > > > http://support.apple.com/kb/ht2355 > > > Yep, and that article stated: > > "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." > > In my case, performance is the main bottleneck, not any > file system "inconsistency" that may happen every 3 years. So this should tell you: 1) journaling isn't a placebo. 2) in individual cases journaling may or may not be worth whatever performance hit it comes with. Thus your question is answered.
From: Priam on 30 May 2010 15:42 On 05/30/2010 12:56 PM, Mark Conrad wrote: > In my case, performance is the main bottleneck, not any > file system "inconsistency" that may happen every 3 years. I don't believe you would see much of a performance decrease by writing a journal on a filesystem where files are 100G large.
From: Mark Conrad on 30 May 2010 16:50
In article <htueur$poo$1(a)news.eternal-september.org>, Priam <priam(a)notsosure.com> wrote: > > In my case, performance is the main bottleneck, not any > > file system "inconsistency" that may happen every 3 years. > > I don't believe you would see much of a performance decrease > by writing a journal on a filesystem where files are 100G large. That is what I thought also. That brings up the question why they worded their explanation to sound like journaling "was bad" for huge files, namely : "...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." That sounds to me like they are saying if you merely READ any large file, you are suffering a performance hit by having journaling on. I wish Apple had made that passage a lot clearer, for the non-geeks they were supposedly making the explanation for. Perhaps someone here can "interpret" what Apple means by that passage. Mark- |