Re: recovering from a power outage

2009-02-16 Thread Mel
On Thursday 12 February 2009 16:24:25 A. Wright wrote:

 Can anyone corroborate that?  If so, does anyone know when
 ed started wanting to make a temp file even before any edits
 are made?  I am sure that ed has gotten me out of similar jams
 in the past, when I wanted to see part of a file in an unchecked
 root fs, and cat wouldn't fit the bill because the file was
 too long (and more and friends are far away on /usr, and therefore
 not available if still patching up the root).

From ed(1):
FILES
 /tmp/ed.*  buffer file

Solution:
mdconfig -a -t swap -s 64m -o reserve -u 0
newfs -U /dev/md0
mount /dev/md0 /tmp
chmod 1777 /tmp

Also, there's /rescue/vi (since 7.0 I believe), which will complain 
about /var/tmp/vi.recover, which you can a) ignore or b) use above procedure 
with -u 1 to create /var/tmp.
-- 
Mel

Problem with today's modular software: they start with the modules
and never get to the software part.
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Re: recovering from a power outage

2009-02-13 Thread Polytropon
On Thu, 12 Feb 2009 23:00:16 -0500, Robert Huff roberth...@rcn.com wrote:
   1) It was my understanding one has to force-mount a dirty
 filesuystem.  IF this sounds like a practice best left to senior
 Jedi Masters ... it porbably is.

Mounting possibly defective file systems is not a good idea. If it's
possible, boot into SUM via boot -s first, check partitions (unmounted!)
and then mount -a. Use exit to bring up MUM afterwards.

Setting background_fsck=NO in /etc/rc.conf may increase boot time
if problems occur, but can be useful to first check for errors, and
then bring up the system, instead of bringing up the system with maybe
problems on the partitions. I think this delay is something you can
affort.

It's not good to fsck a mounted partition anyway, because fsck can
repair minor defects on its own.



   2) I would _never_ let background fsck take care of things
 after a crash,  While hovering over the keyboard is a pain, I will
 find out how badly things are damaged, rather than have boatloads of
 files mysteriously vanish.

That's a good concept which I do follow myself, too. I spend some minutes
seeing fsck checking partitions after unclean shutdown, but when everything's
okay, there's no problem running into MUM *afterwards*.


-- 
Polytropon
From Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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Re: recovering from a power outage

2009-02-13 Thread Wojciech Puchar

seeing fsck checking partitions after unclean shutdown, but when everything's
okay, there's no problem running into MUM *afterwards*.


exactly like me i have
background_fsck=NO

in rc.conf

unix doesn't crash every few hours so it's really not a problem to wait a 
bit more

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Re: recovering from a power outage

2009-02-13 Thread Robert Huff

Wojciech Puchar writes:

  background_fsck=NO
  
  in rc.conf
  
  unix doesn't crash every few hours so it's really not a problem
  to wait a bit more

Cases and personal tolerance may vary.
One of my machines has a pair of 50gb SCSI disks; running two
full passes takes about 7 minutes.
I have no idea how long it might take to check a multi-terabyte
RAID-mumble set-up.
Still worth waiting ... in my opinion.


Robert Huff




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Re: recovering from a power outage

2009-02-13 Thread Polytropon
On Fri, 13 Feb 2009 08:11:56 -0500, Robert Huff roberth...@rcn.com wrote:
   One of my machines has a pair of 50gb SCSI disks; running two
 full passes takes about 7 minutes.
   I have no idea how long it might take to check a multi-terabyte
 RAID-mumble set-up.

It's not *that* hard to wait for an fsck. I have 2 x 500 GB here at home,
you're right, it takes several minutes for fsck to check both disks, but
in the end, you're happy that either everything turns out to be okay or,
if problems occured, you see these problems and can decide how to handle
them.



   Still worth waiting ... in my opinion.

I'd rather wait than lose data.

But as you said, it's very individual how you think about this. If backups
are done properly, sometimes it might even be easier *not* to repair data,
but to put back the backups on the newly initialized disks...



-- 
Polytropon
From Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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Re: recovering from a power outage

2009-02-13 Thread Jerry
On Fri, 13 Feb 2009 14:16:13 +0100
Polytropon free...@edvax.de wrote:

 On Fri, 13 Feb 2009 08:11:56 -0500, Robert Huff roberth...@rcn.com
 wrote:
 One of my machines has a pair of 50gb SCSI disks; running two
 full passes takes about 7 minutes.
 I have no idea how long it might take to check a
 multi-terabyte RAID-mumble set-up.

 It's not *that* hard to wait for an fsck. I have 2 x 500 GB here at
 home, you're right, it takes several minutes for fsck to check both
 disks, but in the end, you're happy that either everything turns out
 to be okay or, if problems occured, you see these problems and can
 decide how to handle them.

 Still worth waiting ... in my opinion.

 I'd rather wait than lose data.
 
 But as you said, it's very individual how you think about this. If
 backups are done properly, sometimes it might even be easier *not* to
 repair data, but to put back the backups on the newly initialized
 disks...

IMHO, if you are running a system where 'power outages' cannot be
tolerated, why not install a UPS, they are really quite cheap, and be
done with it? I cannot imagine any high end, mission critical
system not employing one.

-- 
Jerry
ges...@yahoo.com

Your temporary financial embarrassment will
be relieved in a surprising manner.


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Re: recovering from a power outage

2009-02-13 Thread Wojciech Puchar

One of my machines has a pair of 50gb SCSI disks; running two
full passes takes about 7 minutes.
I have no idea how long it might take to check a multi-terabyte
RAID-mumble set-up.


depends of how filesystem was created.
multiterabyte arrays are usually used for large files, and filesystem with 
64K blocks and 8K fragments and say one inode/megabyte is checked VERY 
quickly.



Still worth waiting ... in my opinion.


Robert Huff






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Re: recovering from a power outage

2009-02-13 Thread Robert Huff


IMHO, if you are running a system where 'power outages' cannot
be tolerated, why not install a UPS, they are really quite
cheap, and be done with it? I cannot imagine any high end,
mission critical system not employing one.

Power outages are not the only thing which can cause (directly
or indirectly) file system corruption.


Robert Huff

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Re: recovering from a power outage

2009-02-13 Thread Jerry
On Fri, 13 Feb 2009 10:22:55 -0500
Robert Huff roberth...@rcn.com wrote:

 IMHO, if you are running a system where 'power outages' cannot
 be tolerated, why not install a UPS, they are really quite
 cheap, and be done with it? I cannot imagine any high end,
 mission critical system not employing one.  

 Power outages are not the only thing which can cause (directly
 or indirectly) file system corruption.

I agree, a sledge hammer applied to the HD could also cause irreparable
harm; however, the subject of this thread referred to 'power outages'.
The use of UPS, RAID, backups, etc. all tend to insure the safety of
data. In this case, the OP only referenced 'power outages'.

-- 
Jerry
ges...@yahoo.com

People that can't find something to live for always seem to find
something to die for.  The problem is, they usually want the rest of us
to die for it too.


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Re: recovering from a power outage

2009-02-13 Thread Polytropon
On Fri, 13 Feb 2009 10:22:55 -0500, Robert Huff roberth...@rcn.com wrote:
   Power outages are not the only thing which can cause (directly
 or indirectly) file system corruption.

Oh yes, that's so true - I experienced it in July 2008, and I still
think it was a software problem...


-- 
Polytropon
From Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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Re: recovering from a power outage

2009-02-13 Thread David Newman
On 2/13/09 7:22 AM, Robert Huff wrote:
 
IMHO, if you are running a system where 'power outages' cannot
be tolerated, why not install a UPS, they are really quite
cheap, and be done with it? I cannot imagine any high end,
mission critical system not employing one.
 
   Power outages are not the only thing which can cause (directly
 or indirectly) file system corruption.

Hi, I'm the OP :-)

To that point, the system in question is attached to a 5000VA UPS. I did
something stupid with the UPS control software that caused an, er,
unscheduled shutdown. No UPS can help Mr. Fat Finger!

Thanks for all your replies.

dn

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recovering from a power outage

2009-02-12 Thread David Newman
What's the canonical method for checking ufs file systems on a FreeBSD
7.1/amd64 system after an unscheduled power outage?

thanks

dn


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Re: recovering from a power outage

2009-02-12 Thread Jerry McAllister
On Thu, Feb 12, 2009 at 04:06:49PM -0800, David Newman wrote:

 What's the canonical method for checking ufs file systems on a FreeBSD
 7.1/amd64 system after an unscheduled power outage?

How about fsck 

jerry


 
 thanks
 
 dn
 
 
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Re: recovering from a power outage

2009-02-12 Thread David Newman
On 2/12/09 4:41 PM, Jerry McAllister wrote:
 On Thu, Feb 12, 2009 at 04:06:49PM -0800, David Newman wrote:
 
 What's the canonical method for checking ufs file systems on a FreeBSD
 7.1/amd64 system after an unscheduled power outage?
 
 How about fsck 

Right. I'm asking procedurally how that's invoked -- eg., do I need to
boot into single-user mode, what filesystem(s) do I mount and how, what
switches if any do I use with fsck and so on.

thanks!

dn


 
 jerry
 
 
 thanks

 dn


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Re: recovering from a power outage

2009-02-12 Thread Tim Judd

David Newman wrote:

On 2/12/09 4:41 PM, Jerry McAllister wrote:
  

On Thu, Feb 12, 2009 at 04:06:49PM -0800, David Newman wrote:



What's the canonical method for checking ufs file systems on a FreeBSD
7.1/amd64 system after an unscheduled power outage?
  
How about fsck 



Right. I'm asking procedurally how that's invoked -- eg., do I need to
boot into single-user mode, what filesystem(s) do I mount and how, what
switches if any do I use with fsck and so on.

thanks!

dn


  

jerry




thanks

dn
  


It's part of the bootup scripts now.  It runs in the background 60 
seconds after the login prompt shows up (not exactly, but close to 60 secs)


it's the background_fsck option that defaults to YES in /etc/rc 
startup.  only if there's major problems will it bail out, screaming for 
help.  it'll drop you into a shell telling you that the filesystems need 
repair.


--Tim
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Re: recovering from a power outage

2009-02-12 Thread prad
On Thu, 12 Feb 2009 16:45:18 -0800
David Newman dnew...@networktest.com wrote:

 do I need to
 boot into single-user mode, what filesystem(s) do I mount and how,
 what switches if any do I use with fsck and so on.

i thought it happens in the background anyway. i don't recall having to
do anything other than listen to the drive whirring away - and we've
had many power outages!

-- 
In friendship,
prad

  ... with you on your journey
Towards Freedom
http://www.towardsfreedom.com (website)
Information, Inspiration, Imagination - truly a site for soaring I's
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Re: recovering from a power outage

2009-02-12 Thread A. Wright


 [ deletia introducing discussion of fsck ]

On Thu, 12 Feb 2009, Tim Judd wrote:

It's part of the bootup scripts now.  It runs in the background 60 seconds 
after the login prompt shows up (not exactly, but close to 60 secs)


it's the background_fsck option that defaults to YES in /etc/rc startup. 
only if there's major problems will it bail out, screaming for help.  it'll 
drop you into a shell telling you that the filesystems need repair.



If you are paranoid (like I am) and want to watch everything
happen, then it is nice that fsck will read /etc/fstab (if still
present) and correlate filesystem names with devices, so you can
just follow a sequence like this:

(boot single user)
fsck /
fsck /usr
fsck /var

...etc

Once you have run fsck on /, you can mount it using
mount -u -o rw /

so that you can then run ed (which is in /bin).

I am assuming that the reason you cannot use ed to look at
a file until this point is because it wants to write the
temporary buffer somewhere, even if there are no changes,
and if / is readonly and nothing else is mounted, then /tmp
is unavailable for this purpose.

Can anyone corroborate that?  If so, does anyone know when
ed started wanting to make a temp file even before any edits
are made?  I am sure that ed has gotten me out of similar jams
in the past, when I wanted to see part of a file in an unchecked
root fs, and cat wouldn't fit the bill because the file was
too long (and more and friends are far away on /usr, and therefore
not available if still patching up the root).

Anyone?

Andrew.

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Re: recovering from a power outage

2009-02-12 Thread Jamie





On Thu, 12 Feb 2009, David Newman wrote:


On 2/12/09 4:41 PM, Jerry McAllister wrote:

On Thu, Feb 12, 2009 at 04:06:49PM -0800, David Newman wrote:


What's the canonical method for checking ufs file systems on a FreeBSD
7.1/amd64 system after an unscheduled power outage?


How about fsck


Right. I'm asking procedurally how that's invoked -- eg., do I need to
boot into single-user mode, what filesystem(s) do I mount and how, what
switches if any do I use with fsck and so on.



   Normally after booting after a power outage fsck will run automatically 
as part of the system startup, and will prune the filesystems 
automatically. If it finds an error it can't fix without help, it will 
drop you into a command line and tell you that there were errors that 
require your input to fix.


   At that point you can just run fsck {reported filesysem with errors} 
ie:


fsck /dev/ad0s1e

   Sometimes you may want to use the -y switch, but use it with caution.

man fsck  for more info on other options.




  - Jamie



thanks!

dn




jerry



thanks

dn


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Re: recovering from a power outage

2009-02-12 Thread Jerry McAllister
On Thu, Feb 12, 2009 at 05:16:53PM -0800, prad wrote:

 On Thu, 12 Feb 2009 16:45:18 -0800
 David Newman dnew...@networktest.com wrote:
 
  do I need to
  boot into single-user mode, what filesystem(s) do I mount and how,
  what switches if any do I use with fsck and so on.
 
 i thought it happens in the background anyway. i don't recall having to
 do anything other than listen to the drive whirring away - and we've
 had many power outages!

It does run in the background, but if you have time, it isn't a 
bad idea to run it in single user before bring the whole system
back up in the circumstance of a catastrophic failure like a power
outage.

jerry

 
 -- 
 In friendship,
 prad
 
   ... with you on your journey
 Towards Freedom
 http://www.towardsfreedom.com (website)
 Information, Inspiration, Imagination - truly a site for soaring I's
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Re: recovering from a power outage

2009-02-12 Thread Robert Huff

Jerry McAllister writes:

do I need to
boot into single-user mode, what filesystem(s) do I mount and how,
what switches if any do I use with fsck and so on.
   
   i thought it happens in the background anyway. i don't recall having to
   do anything other than listen to the drive whirring away - and we've
   had many power outages!
  
  It does run in the background, but if you have time, it isn't a 
  bad idea to run it in single user before bring the whole system
  back up in the circumstance of a catastrophic failure like a power
  outage.

1) It was my understanding one has to force-mount a dirty
filesuystem.  IF this sounds like a practice best left to senior
Jedi Masters ... it porbably is.
2) I would _never_ let background fsck take care of things
after a crash,  While hovering over the keyboard is a pain, I will
find out how badly things are damaged, rather than have boatloads of
files mysteriously vanish.


Robert Huff



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Re: recovering from a power outage

2009-02-12 Thread Bill Moran
David Newman dnew...@networktest.com wrote:

 What's the canonical method for checking ufs file systems on a FreeBSD
 7.1/amd64 system after an unscheduled power outage?

Wait.

The system will automatically detect a dirty shutdown and check the disks
during the boot process.  If the disks are only mildly scrambled by the
outage, the system will continue to boot and the filesystem check program
will run in the background -- you'll notice some disk slowness until
fsck is done cleaning things up, but things will be otherwise fine.

See the man page for fsck and fsck_ffs for more details.

-- 
Bill Moran
http://www.potentialtech.com
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