[H-GEN] Idea for journalling filesystems

Paul Gearon pag at PISoftware.com
Sun Jun 29 21:00:00 EDT 2003


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Oh, I do love the formatting Jason.  Well done.  :-)


On Sun, 29 Jun 2003, Jason Parker-Burlingham wrote:

> As many of you know I run XFS at home, so I am a
> bit biased toward it, but since mkfs.xfs(8) allows you to say where
> the log device is (the logdev=/dev/sdfoo option),

Yes, I know that XFS was one of the earliest (was it THE earliest?)
journalling file systems to hit Linux kernel.  (Don't forget that we owe
this technology to SCO!  Hmmm, how did SGI get it if IBM misappropriated
it?  But I digress...)  However, I personally have had no difficulty with
both Reiser and ext3, and both of these provide identical log device
options.

I'll admit that I haven't put either filesystem under pressure, so for an
enterprise installation it'd be worthwhile researching the limitations.
However, I've been using both of them on a day-to-day basis for some time
now with no issues at all.

I thought it might be worth mentioning, since almost all systems run ext2
filesystems, and adding journalling to an existing filesystem is a simple
matter of running tune2fs.  Conversely, it's just as easy to *remove* a
journal, in case anything happens to the journal device.

> why not create it on one of those neato USB keychain drive thingies?

The only hassle I see is that there is a limit to how often flash may be
written to (it's getting better over time, but the limit is still there).
For the typical use of copying files to and from a USB drive, the flash
need only expect to be written to a couple of times a day.  As a logging
device it could be written to hundreds of times a day (if not more...
YMMV).  I'd be worried that after a couple of months of this kind of usage
the drive would start to behave unreliably.

If you don't want moving parts, then you could try those RAM-based solid
state hard drives (the ones which use RAM and batteries).  Unfortunately,
they're prohibitively expensive.

Regards,
Paul Gearon

Software Engineer                Telephone:   +61 7 3876 2188
Plugged In Software              Fax:         +61 7 3876 4899
http://www.PIsoftware.com        PGP Key available via finger

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(Translation from latin: "I have a catapult. Give me all the money,
or I will fling an enormous rock at your head.")



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