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Old 01-01-2011, 07:35 AM
Philip Webb
 
Default Good file system that recovers from a power failure.

110101 Philip Webb wrote:
> typically in the very early morning when their doing maintenance:

Sorry, it's early in my day: that sb "they're" (red face).

--
========================,,======================== ====================
SUPPORT ___________//___, Philip Webb
ELECTRIC /] [] [] [] [] []| Cities Centre, University of Toronto
TRANSIT `-O----------O---' purslowatchassdotutorontodotca
 
Old 01-01-2011, 11:47 AM
Mick
 
Default Good file system that recovers from a power failure.

On Friday 31 December 2010 22:11:37 Volker Armin Hemmann wrote:
> reiser4 is fully atomic. A transactions happens completely or it doesn't.
>
> Unlike ext4 or btrfs or xfs.
>
> reiser4 also uses barriers (the others use them too, but), when barriers
> are not available for some reason or another, it complains in dmesg and
> goes into sync mode.
>
> This combined makes it pretty robust against power failures. You won't get
> the good old xfs/ext4/btrfs problem that a rename can end with two useless
> empty files.

I read what Volker is saying and it sounds impressive from a fs design
perspective, but my experience does not concur with it.

I have a had a power cut (run out of battery) and the fs got corrupted. :-(

This however may not be a conclusive finding. I was running reiser4 for about
a year on my laptop. Unfortunately, I have a had a large number of fs
corruptions, most of which appeared to be random. The last one just before
Christmas proved to be fatal and unrecoverable with fsck.reiser4.

I could try to blame the disk, but the MSWindows ntfs which I dual boot to
from the same disk never failed or corrupted (admittedly though it has seen
hardly any use).

I have to say that when it did run without corruption reiser4 is an
exceptional fs in terms of performance. With the exception of mounting large
partitions which takes some time, I don't think anything else I've tried comes
close. If I were to build a desktop which unlike a laptop is not bounced
around when commuting on trains and what not, I would probably try it again
(because I have a niggling suspicion that the cause of my problems might have
been a mechanical reason).

Either way, I can say with some certainty that power cuts and running out of
space on a partition brought about fs corruption with reiser4.

I have now moved all but one of my partitions to ext4 and will wait to see
what happens with that, but 11 months on reiser4 has left a bad taste in my
mouth.

Historically, I have mostly used reiserfs and xfs. Reiserfs is in my
experience very reliable and easily recoverable and I can assuredly echo
Alan's findings. Some years ago I had a faulty memory controller which would
hard lock an old desktop. At least once a day (typically in the middle of an
emerge, or updatedb) it would crash badly and I would have to pull he plug.
In as many as 4 years I must have had hundreds and hundreds of hard reboots.
I vaguely recall one or two fs corruptions on only one or two partitions.
reiserfsck did recover the fs every single time without major drama.

If bleeding edge performance is not an issue I would recommend reiserfs to
mitigate the risk from powercuts.
--
Regards,
Mick
 
Old 01-01-2011, 12:02 PM
Volker Armin Hemmann
 
Default Good file system that recovers from a power failure.

Hi,

there is one scenario that is troublesome:

mldonkey temp files.

If you don't use mldonkey/amule/$whatever you should be fine.
 
Old 01-01-2011, 12:34 PM
Dale
 
Default Good file system that recovers from a power failure.

Philip Webb wrote:

110101 Philip Webb wrote:


typically in the very early morning when their doing maintenance:


Sorry, it's early in my day: that sb "they're" (red face).




That's OK. I got a cell phone too. I do pretty good with text speak. lol

Dale

:-) :-)
 
Old 01-02-2011, 01:31 AM
William Kenworthy
 
Default Good file system that recovers from a power failure.

On Fri, 2010-12-31 at 19:12 -0600, Dale wrote:
> Alan McKinnon wrote:
> > Apparently, though unproven, at 00:27 on Saturday 01 January 2011, Dale did
> > opine thusly:
> >
> >
> >
> >>> It's my opinion that reiser is in security-fix-only mode from whoever is
> >>> maintaining it. If everything else around it stays the same, the fs will
> >>> obviously continue working just as it always did. But the surrounding
> >>> system is not stable, it changes rapidly, especially in kernel space, so
> >>> the odds are stacked against reiser for bitrot. For all these reasons, I
> >>> regretfully switched my own systems over to ext4 some time ago. Rieser
> >>> was a good fs whose time has come and gone and I no longer had warm and
> >>> fuzzies about the future with it.
> >>>
> >> I'm not sure I EVER saw a update to reiserfs. I was hoping it was just
> >> that good. lol
> >>
> >> This is also the reason I was considering moving to ext4 or something.
> >> How has ext4 been treating you since the switch? I also assume you have
> >> UPSs as well?
> >>
> > It's still early days, but ext4 has been good here on all machines. I don't
> > have a UPS (couldn't be bothered really...) so the UPS is the device's
> > battery. Which means me doing something really stupid and locking the machine
> > up is the most common reason for hard reboots. It survived every time so far.
> >
> >
>
> That sounds good. Your situation is not a theory but real and in
> practice. We all know what happens to theories. :-(
>
> Dale
>
> :-) :-)
>

As someone who suffered from a rare, but fatal bug in some kernel
updates to reiserfs3 which were only fixed in a recent versions, I can
say yes, its still being actively maintained.

But, I am thinking its time to move on - in particular something that
can fsck online (my mythtv and backup archives on reiserfs have to be
done offline and its takes hours to do terrabytes!) and still be robust.

I use "dirvish" for backups which creates a LOT of hardlinks which can
be very hard on a file system. ext2 typically lasts only a few cycles,
while ext3 is only a little better even with full journalling. Coupled
to the fact neither is very good with power cuts and they are a worst
case choice for data security

Reiserfs3 by contrast is very very good, with only a few instances of
problems over many years (since beore 3 was even in the kernel) - none
of which have lost critical data or file systems (ext2/3 devs, are you
listening Even the "slowpath" bug I ran into just required a kernel
downgrade and an fsck until later kernel versions fixed the bug.

I am now trying btrfs and am very impressed. On line fsck is wonderful
and I have had one instace of corruption due to a flakey hard disk - the
partition is on lvm so I moved it to another disk in the array and its
been solid since - didnt lose it or any any data. The dirvish backups
are fast enough (impression only, no timings) but large scale deleted
(60Gb copies of laptops etc) are much slower than reiserfs. My only
"glitch" has been dirvish/btrfs inability to deal with a ".gvfs" file in
some home directories - it has some wierd permissions but an exclusion
from the backup regime bypasses it. reiserfs doesn't have a problem
with it.

So, for me at least, btrfs is looking like the way forward. Its in
"testing" at the moment, but I am ready to move whole systems over to
it.

BillK



--
William Kenworthy <billk@iinet.net.au>
Home in Perth!
 
Old 01-02-2011, 05:33 AM
"Walter Dnes"
 
Default Good file system that recovers from a power failure.

On Sat, Jan 01, 2011 at 03:09:24AM -0500, Philip Webb wrote

> > Total corruptions in 5 years with reiserfs-3.6
> > and NO ups in that environment = zero.
>
> Same here: I've used Reiserfs since 2003 & never had a problem;

<AOL> Me too </AOL>. Reiserfs 3 for several years and no lost data.

--
Walter Dnes <waltdnes@waltdnes.org>
 
Old 01-03-2011, 01:06 AM
"Walter Dnes"
 
Default Good file system that recovers from a power failure.

On Sun, Jan 02, 2011 at 10:31:42AM +0800, William Kenworthy wrote

> I use "dirvish" for backups which creates a LOT of hardlinks which can
> be very hard on a file system. ext2 typically lasts only a few cycles,
> while ext3 is only a little better even with full journalling. Coupled
> to the fact neither is very good with power cuts and they are a worst
> case choice for data security

Am I mis-understanding or are you mis-speaking? hardlinks != backup
A hardlink is simply another pointer to the same tracks/sectors on disk.
If the on-disk data is destroyed it doesn't matter how many pointers you
have to the data, it's gone. A real backup is another copy of the data
on another drive, preferably external.

> Reiserfs3 by contrast is very very good, with only a few instances of
> problems over many years (since beore 3 was even in the kernel) - none
> of which have lost critical data or file systems (ext2/3 devs, are you
> listening

I don't think ext2fs is being developed as such. And ext3fs is mostly
a journalling system backported to ext2fs. ext2fs was written way back
when in January 1993, and the specs were uptodate for then, but our
expectations, and disk sizes have grown since then.

> So, for me at least, btrfs is looking like the way forward. Its in
> "testing" at the moment, but I am ready to move whole systems over
> to it.

I'm on reiserfs3 for now. Hopefully, it'll be maintained until ext4
or btrfs or whatever is deemed ready for primetime. When that happens,
I'll do any new installs on the new filesystem. If it works, don't muck
around with it. Unless support/maintenance for reiserfs3 is dropped or
a new fs comes out with a feature I really want/need, I won't migrate
existing systems.

--
Walter Dnes <waltdnes@waltdnes.org>
 
Old 01-03-2011, 02:36 AM
William Kenworthy
 
Default Good file system that recovers from a power failure.

Reply inline

On Sun, 2011-01-02 at 21:06 -0500, Walter Dnes wrote:
> On Sun, Jan 02, 2011 at 10:31:42AM +0800, William Kenworthy wrote
>
> > I use "dirvish" for backups which creates a LOT of hardlinks which can
> > be very hard on a file system. ext2 typically lasts only a few cycles,
> > while ext3 is only a little better even with full journalling. Coupled
> > to the fact neither is very good with power cuts and they are a worst
> > case choice for data security

> Am I mis-understanding or are you mis-speaking? hardlinks != backup
> A hardlink is simply another pointer to the same tracks/sectors on disk.
> If the on-disk data is destroyed it doesn't matter how many pointers you
> have to the data, it's gone. A real backup is another copy of the data
> on another drive, preferably external.
>

Yes you have misunderstood, check out http://www.dirvish.org/. Basicly
the first backup (--init) is a complete copy of the source into either a
local disk or remote storage. Subsequent backups create a new image, by
checking if the previous copy of a file/directory/whatever has changed
and if not it will create a hardlink, but if changed will make a new
copy. So you can have full, daily backups using typically only 2x the
original space for many versioned backups. As only changed files are
copied, its only changes that use "real" space.

Restore is just copy the version back you want. Full OS restore is done
in a similar fashion to copying one system to another (i.e., cloned from
the image).



> > Reiserfs3 by contrast is very very good, with only a few instances of
> > problems over many years (since beore 3 was even in the kernel) - none
> > of which have lost critical data or file systems (ext2/3 devs, are you
> > listening
>
> I don't think ext2fs is being developed as such. And ext3fs is mostly
> a journalling system backported to ext2fs. ext2fs was written way back
> when in January 1993, and the specs were uptodate for then, but our
> expectations, and disk sizes have grown since then.
>
> > So, for me at least, btrfs is looking like the way forward. Its in
> > "testing" at the moment, but I am ready to move whole systems over
> > to it.
>
> I'm on reiserfs3 for now. Hopefully, it'll be maintained until ext4
> or btrfs or whatever is deemed ready for primetime. When that happens,
> I'll do any new installs on the new filesystem. If it works, don't muck
> around with it. Unless support/maintenance for reiserfs3 is dropped or
> a new fs comes out with a feature I really want/need, I won't migrate
> existing systems.
>
Exactly, I have had great service from reiserfs3, but fscking terrabytes
of storage is becoming a serious limitation when it means taking a
system offline to do so. That being said, I only do it every 6 months
or so as a precaution rather than the expectation of finding something
wrong - and haven't unless it was an actual disk failure (that one was
at least 18 months ago.

BillK
 

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