[H-GEN] Idea for journalling filesystems

[Jason Parker-Burlingham]

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Paul Gearon <pag at PISoftware.com> writes:

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

A boy's gotta have a hobby.

> 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.

As I just reported in another post, XFS is one of the older
filesystems available for Linux full stop.

> 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.

People keep saying this.  My view is that if I am going to switch
filesystem I am going to take the opportunity that presents to back
up, replace drives, repartition, and reinstall.  Done right, that
leaves me with two disks with the same data on, and a tape with an
image of at least the important contents.

The other reason I prefer the XFS tools is the consistent interface
they present, which in marked difference to the ext2 or 3 tools, uses
sensible option names and formats, along with excellently written
manual pages (the ext ones are inconsistent---it's not always clear
how one should count blocks, nor is the bad block list format laid
out, etc).

>> 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).

Bugger!  Do you have a source for this information?  It would indeed
be a show-stopper for what's otherwise an excellent idea.  Trying to
track down specs on these drives isn't exactly easy.  I'll take a poke
at IBM's website, next.

> 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).

Probably thousands or tens of thousands, to be honest.

> 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.

Yeah, the low cost of these units is what attracted me to them in the
first place.
-- 
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                                 http://www.panix.com/~jasonp

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