Journaling - any benefits for a MacBook?
in [Mac Systems]
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From: Bob Harris on 30 May 2010 22:42 In article <300520101350032868%aeiou(a)mostly.invalid>, Mark Conrad <aeiou(a)mostly.invalid> wrote: > 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- My day job is working on commercial Unix file systems w/journaling. The Journal writes all the file metadata. The metadata would include, directory name entry changes, changes to file metadata such as all the following stat information: stat -x tmp.tmp File: "tmp.tmp" Size: 716 FileType: Regular File Mode: (0644/-rw-r--r--) Uid: ( 501/ harris) Gid: ( 501/ harris) Device: 14,2 Inode: 62873098 Links: 1 Access: Sun May 30 21:25:34 2010 Modify: Sun May 30 21:25:34 2010 Change: Sun May 30 21:25:34 2010 And with respect to big files, all the storage allocations. This means updating the storage extent map in the file each time the file is extended as it grows. And Journaling is also used when updating all the file system global information, such as when you create a new file, the inode that was allocated for the file, needs to be removed from a global file system list. When you allocation storage for a file, that storage needs to be allocated from a global free list. So back to big files, most files are grown not preallocated, so there is storage allocation constantly while the file is being created. That is journal entries as the storage is added to the file, journal entries to update the file modification time, the file size information, journal entries to remove that storage from the storage free list. HOWEVER, I strongly recommend using journalling unless you have a demonstrated performance penalty and turning off journalling is the solution. Consumer file systems are now commonly terabytes in size, with millions of files on a single file system. A power failure or system crash on a file system without journalling, is going to run fsck (File System Check utility) on the file system before mounting that file system. Besides taking a long time, it is going to concentrate high disk activity such that your disk is going to be running hot for hours, which is going to be a lot of "ware and tare" on your disk drive. If your disk is old (3 years is old for a disk these days) and marginal, this might be the "Last nail in the coffin" for that drive. Bob Harris
From: John Albert on 30 May 2010 23:16 RE: "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." Agreed. I have never used journaling, ever, across multiple Macs, drives, and partitions. Seems to work just fine. - John
From: Priam on 30 May 2010 23:42 On 05/30/2010 11:24 PM, Mark Conrad wrote: > If THAT does not get it cooking, then I have to pay the $40 per > phone call that Nuance charges to support Dragon, being very > careful to avoid telling them I am running it on Mac hardware. You're sure that's not the problem?
From: Priam on 30 May 2010 23:46 On 05/30/2010 09:47 PM, Mark Conrad wrote: > When I rattle off dictation like this, the poor Mac Mini grunts and > groans, glowing a dull red from heat, so I am forced to slow down > my dictation to 60 wpm. It's funny. You have only praise for Dragon, which runs on Windows. Why don't you get a $1000 PC beast (i7. 6GB RAM, 2 TB HDs, etc.) that won't choke like a lame Mini?
From: Steve Hix on 30 May 2010 23:54
In article <4c032a6e$0$22856$2c56edd9(a)usenetrocket.com>, John Albert <j.albert(a)snet.net> wrote: > RE: > "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." > > Agreed. > > I have never used journaling, ever, across multiple Macs, > drives, and partitions. > > Seems to work just fine. And I use it on all my Mac systems (and my wife's, etc.) Never had a problem, never noticed any performance issues. Then again, I spent more than 20 years working around Solaris and SunOS systems, and I'm used to it. |