RE: Raid Failed What to to

RE: Raid Failed What to to

[Dominik Sennfelder]

Hello

Thanks for your help.
I created the array with mkraid /dev/md0 after i added the entrys in
/etc/raidtab.
I analyzed the logs an saw that one disk failed one day before,
so the raid run with 3 discs. My fault was to raidsetfault the wrong drive.
But in that moment the Raid broke up an no write was possilble because it
got remountet -ro. After i hotadded it again, it tried to sync but with only
two discs syncing wouldn't be possible. The drive i removed wan't really
faulty, it was just set faulty. I even could browse the filesystem when just
2 discs run. 
So can i reassamble the drive mith mdadm? or do i have to use mkraid?

Thanks for your help and suggestions.

Dominik


> This is an example for using mdadm where the second of three disks is bad.
> But you must use the same chunk size and other RAID5 parameters or the
> array
> will have bogus data.  It would be nice if you still have the original
> command you used to create the array.
> 
> mdadm -C /dev/md0 -l 5 -n 3 /dev/hda3 missing /dev/hdc3
> 
> Guy
> 
> -----Original Message-----
> From: Guy [mailto:bugzilla@watkins-home.com] 
> Sent: Friday, May 21, 2004 10:00 AM
> To: 'Clemens Schwaighofer'; 'Dominik Sennfelder'
> Cc: 'linux-raid@vger.kernel.org'
> Subject: RE: Raid Failed What to to
> 
> If you re-make the array with the same parameters as it has now the data
> will not be lost (assuming it is still there now).  If 1 disk is really
> bad
> then leave it out.
> 
> The procedures depend on which program you use to create the array.  Do
> you
> use mkraid or mdadm?
> 
> Guy
> 
> -----Original Message-----
> From: linux-raid-owner@vger.kernel.org
> [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Clemens
> Schwaighofer
> Sent: Friday, May 21, 2004 4:45 AM
> To: Dominik Sennfelder
> Cc: linux-raid@vger.kernel.org
> Subject: Re: Raid Failed What to to
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Dominik Sennfelder wrote:
> | Hello
> |
> | I have got a Raid 5 with 4 160 GB Disk,
> | On of the Disks Failed because. But I know its OK I had this for some
> | times.
> | A Restart solved The Problem.
> | But now  Tried to raidhotremove the Drive and removed the wrong drive.
> | I just recongized the Problem after i raidhotadded itagain.
> | No the Raid tries to sync again.
> 
> well if you removed two drives from your Raid5 array, it might got
> competly out of sync and then there is no way to recover. I have never
> tried this with my raid, but if you add another disk it well be
> re-synced, ergo it tries to rebuild the array out of the CRCs on the
> other drives, if you remove two, you don't have enough redudant data to
> do this (raid 6 can recover from a 2 drive failure).
> 
> I hope you have a backup.
> 
> - --
> Clemens Schwaighofer - IT Engineer & System Administration
> ==========================================================
> TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
> Tel: +81-(0)3-3545-7703            Fax: +81-(0)3-3545-7343
> http://www.tequila.co.jp
> ==========================================================
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.2.4 (GNU/Linux)
> 
> iD8DBQFArcGmjBz/yQjBxz8RAkYKAJ9TAc03OnmIth/M03xBmopKerZLOQCcCiiG
> wk/lAjdcrd1jPWSoLyOGLAE=
> =5uyj
> -----END PGP SIGNATURE-----
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 

-- 
Mfg Dominik Sennfelder
--------------
Sennfelder@gmx.de         IRC: #spooky  
ICQ: 18164192          Blue Skies          

RE: Raid Failed What to to

[Guy]

mkraid or mdadm will work, just be very sure you use the correct options.
As long as the system does not attempt a re-sync, the data will not be
destroyed.  But if you get the parameters wrong and a re-sync starts, expect
data to be lost.  So, keep 1 disk missing until you are sure you have it
right!

One of the parameters that must be correct: "parity-algorithm".

If you used mkraid your /etc/raidtab file should have what you need.  You
will need to use the "failed-disk" keyword.  See "man raidtab".  I am not
sure how to use it.  So be careful!

Guy

-----Original Message-----
From: Dominik Sennfelder [mailto:Sennfelder@gmx.de] 
Sent: Friday, May 21, 2004 4:59 PM
To: Guy
Cc: linux-raid@vger.kernel.org
Subject: RE: Raid Failed What to to

Hello

Thanks for your help.
I created the array with mkraid /dev/md0 after i added the entrys in
/etc/raidtab.
I analyzed the logs an saw that one disk failed one day before,
so the raid run with 3 discs. My fault was to raidsetfault the wrong drive.
But in that moment the Raid broke up an no write was possilble because it
got remountet -ro. After i hotadded it again, it tried to sync but with only
two discs syncing wouldn't be possible. The drive i removed wan't really
faulty, it was just set faulty. I even could browse the filesystem when just
2 discs run. 
So can i reassamble the drive mith mdadm? or do i have to use mkraid?

Thanks for your help and suggestions.

Dominik


> This is an example for using mdadm where the second of three disks is bad.
> But you must use the same chunk size and other RAID5 parameters or the
> array
> will have bogus data.  It would be nice if you still have the original
> command you used to create the array.
> 
> mdadm -C /dev/md0 -l 5 -n 3 /dev/hda3 missing /dev/hdc3
> 
> Guy
> 
> -----Original Message-----
> From: Guy [mailto:bugzilla@watkins-home.com] 
> Sent: Friday, May 21, 2004 10:00 AM
> To: 'Clemens Schwaighofer'; 'Dominik Sennfelder'
> Cc: 'linux-raid@vger.kernel.org'
> Subject: RE: Raid Failed What to to
> 
> If you re-make the array with the same parameters as it has now the data
> will not be lost (assuming it is still there now).  If 1 disk is really
> bad
> then leave it out.
> 
> The procedures depend on which program you use to create the array.  Do
> you
> use mkraid or mdadm?
> 
> Guy
> 
> -----Original Message-----
> From: linux-raid-owner@vger.kernel.org
> [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Clemens
> Schwaighofer
> Sent: Friday, May 21, 2004 4:45 AM
> To: Dominik Sennfelder
> Cc: linux-raid@vger.kernel.org
> Subject: Re: Raid Failed What to to
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Dominik Sennfelder wrote:
> | Hello
> |
> | I have got a Raid 5 with 4 160 GB Disk,
> | On of the Disks Failed because. But I know its OK I had this for some
> | times.
> | A Restart solved The Problem.
> | But now  Tried to raidhotremove the Drive and removed the wrong drive.
> | I just recongized the Problem after i raidhotadded itagain.
> | No the Raid tries to sync again.
> 
> well if you removed two drives from your Raid5 array, it might got
> competly out of sync and then there is no way to recover. I have never
> tried this with my raid, but if you add another disk it well be
> re-synced, ergo it tries to rebuild the array out of the CRCs on the
> other drives, if you remove two, you don't have enough redudant data to
> do this (raid 6 can recover from a 2 drive failure).
> 
> I hope you have a backup.
> 
> - --
> Clemens Schwaighofer - IT Engineer & System Administration
> ==========================================================
> TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
> Tel: +81-(0)3-3545-7703            Fax: +81-(0)3-3545-7343
> http://www.tequila.co.jp
> ==========================================================
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.2.4 (GNU/Linux)
> 
> iD8DBQFArcGmjBz/yQjBxz8RAkYKAJ9TAc03OnmIth/M03xBmopKerZLOQCcCiiG
> wk/lAjdcrd1jPWSoLyOGLAE=
> =5uyj
> -----END PGP SIGNATURE-----
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 

-- 
Mfg Dominik Sennfelder
--------------
Sennfelder@gmx.de         IRC: #spooky  
ICQ: 18164192          Blue Skies          

RE: Raid Failed What to to

[Dominik Sennfelder]

But it tried to resync after i have added the disc again with raidhotadd. :(
But it could do nothing. in the log file there have bon hundreds of entires
like.
May 20 23:52:25 utgard kernel: md: syncing RAID array md0
May 20 23:52:25 utgard kernel: md: minimum _guaranteed_ reconstruction
speed: 1000 KB/sec/disc.
May 20 23:52:25 utgard kernel: md: using maximum available idle IO bandwith
(but not more than 200000 KB/sec) for reconstruction.
May 20 23:52:25 utgard kernel: md: using 128k window, over a total of
156288256 blocks.
May 20 23:52:25 utgard kernel: md: md0: sync done.
But how you can se this lastet only for 1 second or something like that.

How would this work?
comment out the entries in the /etc/raidtab, boot the system 
set 1 device as faulty ( best would be the one that faild the day before)
and than just mkraid /dev/md0 ?

Dominik


> 2mkraid or mdadm will work, just be very sure you use the correct options.
> As long as the system does not attempt a re-sync, the data will not be
> destroyed.  But if you get the parameters wrong and a re-sync starts,
> expect
> data to be lost.  So, keep 1 disk missing until you are sure you have it
> right!
> 
> One of the parameters that must be correct: "parity-algorithm".
> 
> If you used mkraid your /etc/raidtab file should have what you need.  You
> will need to use the "failed-disk" keyword.  See "man raidtab".  I am not
> sure how to use it.  So be careful!
> 
> Guy
> 
> -----Original Message-----
> From: Dominik Sennfelder [mailto:Sennfelder@gmx.de] 
> Sent: Friday, May 21, 2004 4:59 PM
> To: Guy
> Cc: linux-raid@vger.kernel.org
> Subject: RE: Raid Failed What to to
> 
> Hello
> 
> Thanks for your help.
> I created the array with mkraid /dev/md0 after i added the entrys in
> /etc/raidtab.
> I analyzed the logs an saw that one disk failed one day before,
> so the raid run with 3 discs. My fault was to raidsetfault the wrong
> drive.
> But in that moment the Raid broke up an no write was possilble because it
> got remountet -ro. After i hotadded it again, it tried to sync but with
> only
> two discs syncing wouldn't be possible. The drive i removed wan't really
> faulty, it was just set faulty. I even could browse the filesystem when
> just
> 2 discs run. 
> So can i reassamble the drive mith mdadm? or do i have to use mkraid?
> 
> Thanks for your help and suggestions.
> 
> Dominik
> 
> 
> > This is an example for using mdadm where the second of three disks is
> bad.
> > But you must use the same chunk size and other RAID5 parameters or the
> > array
> > will have bogus data.  It would be nice if you still have the original
> > command you used to create the array.
> > 
> > mdadm -C /dev/md0 -l 5 -n 3 /dev/hda3 missing /dev/hdc3
> > 
> > Guy
> > 
> > -----Original Message-----
> > From: Guy [mailto:bugzilla@watkins-home.com] 
> > Sent: Friday, May 21, 2004 10:00 AM
> > To: 'Clemens Schwaighofer'; 'Dominik Sennfelder'
> > Cc: 'linux-raid@vger.kernel.org'
> > Subject: RE: Raid Failed What to to
> > 
> > If you re-make the array with the same parameters as it has now the data
> > will not be lost (assuming it is still there now).  If 1 disk is really
> > bad
> > then leave it out.
> > 
> > The procedures depend on which program you use to create the array.  Do
> > you
> > use mkraid or mdadm?
> > 
> > Guy
> > 
> > -----Original Message-----
> > From: linux-raid-owner@vger.kernel.org
> > [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Clemens
> > Schwaighofer
> > Sent: Friday, May 21, 2004 4:45 AM
> > To: Dominik Sennfelder
> > Cc: linux-raid@vger.kernel.org
> > Subject: Re: Raid Failed What to to
> > 
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > 
> > Dominik Sennfelder wrote:
> > | Hello
> > |
> > | I have got a Raid 5 with 4 160 GB Disk,
> > | On of the Disks Failed because. But I know its OK I had this for some
> > | times.
> > | A Restart solved The Problem.
> > | But now  Tried to raidhotremove the Drive and removed the wrong drive.
> > | I just recongized the Problem after i raidhotadded itagain.
> > | No the Raid tries to sync again.
> > 
> > well if you removed two drives from your Raid5 array, it might got
> > competly out of sync and then there is no way to recover. I have never
> > tried this with my raid, but if you add another disk it well be
> > re-synced, ergo it tries to rebuild the array out of the CRCs on the
> > other drives, if you remove two, you don't have enough redudant data to
> > do this (raid 6 can recover from a 2 drive failure).
> > 
> > I hope you have a backup.
> > 
> > - --
> > Clemens Schwaighofer - IT Engineer & System Administration
> > ==========================================================
> > TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
> > Tel: +81-(0)3-3545-7703            Fax: +81-(0)3-3545-7343
> > http://www.tequila.co.jp
> > ==========================================================
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v1.2.4 (GNU/Linux)
> > 
> > iD8DBQFArcGmjBz/yQjBxz8RAkYKAJ9TAc03OnmIth/M03xBmopKerZLOQCcCiiG
> > wk/lAjdcrd1jPWSoLyOGLAE=
> > =5uyj
> > -----END PGP SIGNATURE-----
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> > 
> 
> -- 
> Mfg Dominik Sennfelder
> --------------
> Sennfelder@gmx.de         IRC: #spooky  
> ICQ: 18164192          Blue Skies          
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

-- 
cYa Bul|wýf
--------------
Buliwyf@gmx.de         IRC: #spooky   
ICQ: 18164192          Blue Skies          

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RE: Raid Failed What to to

[Guy]

Yes set the failed disk to faulty.
I just am not sure how to do that with mkraid and raidtab.

You will need to read the man pages.

-----Original Message-----
From: Dominik Sennfelder [mailto:buliwyf@gmx.de] 
Sent: Friday, May 21, 2004 6:36 PM
To: Guy
Cc: Sennfelder@gmx.de; linux-raid@vger.kernel.org
Subject: RE: Raid Failed What to to

But it tried to resync after i have added the disc again with raidhotadd. :(
But it could do nothing. in the log file there have bon hundreds of entires
like.
May 20 23:52:25 utgard kernel: md: syncing RAID array md0
May 20 23:52:25 utgard kernel: md: minimum _guaranteed_ reconstruction
speed: 1000 KB/sec/disc.
May 20 23:52:25 utgard kernel: md: using maximum available idle IO bandwith
(but not more than 200000 KB/sec) for reconstruction.
May 20 23:52:25 utgard kernel: md: using 128k window, over a total of
156288256 blocks.
May 20 23:52:25 utgard kernel: md: md0: sync done.
But how you can se this lastet only for 1 second or something like that.

How would this work?
comment out the entries in the /etc/raidtab, boot the system 
set 1 device as faulty ( best would be the one that faild the day before)
and than just mkraid /dev/md0 ?

Dominik


> 2mkraid or mdadm will work, just be very sure you use the correct options.
> As long as the system does not attempt a re-sync, the data will not be
> destroyed.  But if you get the parameters wrong and a re-sync starts,
> expect
> data to be lost.  So, keep 1 disk missing until you are sure you have it
> right!
> 
> One of the parameters that must be correct: "parity-algorithm".
> 
> If you used mkraid your /etc/raidtab file should have what you need.  You
> will need to use the "failed-disk" keyword.  See "man raidtab".  I am not
> sure how to use it.  So be careful!
> 
> Guy
> 
> -----Original Message-----
> From: Dominik Sennfelder [mailto:Sennfelder@gmx.de] 
> Sent: Friday, May 21, 2004 4:59 PM
> To: Guy
> Cc: linux-raid@vger.kernel.org
> Subject: RE: Raid Failed What to to
> 
> Hello
> 
> Thanks for your help.
> I created the array with mkraid /dev/md0 after i added the entrys in
> /etc/raidtab.
> I analyzed the logs an saw that one disk failed one day before,
> so the raid run with 3 discs. My fault was to raidsetfault the wrong
> drive.
> But in that moment the Raid broke up an no write was possilble because it
> got remountet -ro. After i hotadded it again, it tried to sync but with
> only
> two discs syncing wouldn't be possible. The drive i removed wan't really
> faulty, it was just set faulty. I even could browse the filesystem when
> just
> 2 discs run. 
> So can i reassamble the drive mith mdadm? or do i have to use mkraid?
> 
> Thanks for your help and suggestions.
> 
> Dominik
> 
> 
> > This is an example for using mdadm where the second of three disks is
> bad.
> > But you must use the same chunk size and other RAID5 parameters or the
> > array
> > will have bogus data.  It would be nice if you still have the original
> > command you used to create the array.
> > 
> > mdadm -C /dev/md0 -l 5 -n 3 /dev/hda3 missing /dev/hdc3
> > 
> > Guy
> > 
> > -----Original Message-----
> > From: Guy [mailto:bugzilla@watkins-home.com] 
> > Sent: Friday, May 21, 2004 10:00 AM
> > To: 'Clemens Schwaighofer'; 'Dominik Sennfelder'
> > Cc: 'linux-raid@vger.kernel.org'
> > Subject: RE: Raid Failed What to to
> > 
> > If you re-make the array with the same parameters as it has now the data
> > will not be lost (assuming it is still there now).  If 1 disk is really
> > bad
> > then leave it out.
> > 
> > The procedures depend on which program you use to create the array.  Do
> > you
> > use mkraid or mdadm?
> > 
> > Guy
> > 
> > -----Original Message-----
> > From: linux-raid-owner@vger.kernel.org
> > [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Clemens
> > Schwaighofer
> > Sent: Friday, May 21, 2004 4:45 AM
> > To: Dominik Sennfelder
> > Cc: linux-raid@vger.kernel.org
> > Subject: Re: Raid Failed What to to
> > 
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > 
> > Dominik Sennfelder wrote:
> > | Hello
> > |
> > | I have got a Raid 5 with 4 160 GB Disk,
> > | On of the Disks Failed because. But I know its OK I had this for some
> > | times.
> > | A Restart solved The Problem.
> > | But now  Tried to raidhotremove the Drive and removed the wrong drive.
> > | I just recongized the Problem after i raidhotadded itagain.
> > | No the Raid tries to sync again.
> > 
> > well if you removed two drives from your Raid5 array, it might got
> > competly out of sync and then there is no way to recover. I have never
> > tried this with my raid, but if you add another disk it well be
> > re-synced, ergo it tries to rebuild the array out of the CRCs on the
> > other drives, if you remove two, you don't have enough redudant data to
> > do this (raid 6 can recover from a 2 drive failure).
> > 
> > I hope you have a backup.
> > 
> > - --
> > Clemens Schwaighofer - IT Engineer & System Administration
> > ==========================================================
> > TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
> > Tel: +81-(0)3-3545-7703            Fax: +81-(0)3-3545-7343
> > http://www.tequila.co.jp
> > ==========================================================
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v1.2.4 (GNU/Linux)
> > 
> > iD8DBQFArcGmjBz/yQjBxz8RAkYKAJ9TAc03OnmIth/M03xBmopKerZLOQCcCiiG
> > wk/lAjdcrd1jPWSoLyOGLAE=
> > =5uyj
> > -----END PGP SIGNATURE-----
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> > 
> 
> -- 
> Mfg Dominik Sennfelder
> --------------
> Sennfelder@gmx.de         IRC: #spooky  
> ICQ: 18164192          Blue Skies          
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

-- 
cYa Bul|wýf
--------------
Buliwyf@gmx.de         IRC: #spooky   
ICQ: 18164192          Blue Skies          


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Re: Raid Failed What to to

[Dominik Sennfelder]

Looks Bad :(

with mkraid i get the following output in /var/log/syslog

May 23 19:13:47 utgard kernel: md: bind<hde1>
May 23 19:13:47 utgard kernel: md: bind<hdi1>
May 23 19:13:47 utgard kernel: md: bind<hdk1>
May 23 19:13:47 utgard kernel: raid5: device hdk1 operational as raid disk 3
May 23 19:13:47 utgard kernel: raid5: device hdi1 operational as raid disk 2
May 23 19:13:47 utgard kernel: raid5: device hde1 operational as raid disk 0
May 23 19:13:47 utgard kernel: raid5: cannot start dirty degraded array 
for md0
May 23 19:13:47 utgard kernel: RAID5 conf printout:
May 23 19:13:47 utgard kernel:  --- rd:4 wd:3 fd:1
May 23 19:13:47 utgard kernel:  disk 0, o:1, dev:hde1
May 23 19:13:47 utgard kernel:  disk 2, o:1, dev:hdi1
May 23 19:13:47 utgard kernel:  disk 3, o:1, dev:hdk1
May 23 19:13:47 utgard kernel: raid5: failed to run raid set md0
May 23 19:13:47 utgard kernel: md: pers->run() failed ...

so i tried mdadm with the options from raidtab

mdadm -C /dev/md0 -l 5 -c 32 -p left-symmetric -n 4 /dev/hde1 /dev/hdi1 
/dev/hdk1 missing /dev/hdg1

this seems to work, the raid startet without any error
but when i try to mount the array i geht

utgard:~# mount /dev/md0 /mnt/hdd1/
mount: wrong fs type, bad option, bad superblock on /dev/md0,
       or too many mounted file systems

a cfdisk tries to start with with a zero table.

any ideas ?

Dominik


Guy wrote:

>This is an example for using mdadm where the second of three disks is bad.
>But you must use the same chunk size and other RAID5 parameters or the array
>will have bogus data.  It would be nice if you still have the original
>command you used to create the array.
>
>mdadm -C /dev/md0 -l 5 -n 3 /dev/hda3 missing /dev/hdc3
>
>Guy
>
>-----Original Message-----
>From: Guy [mailto:bugzilla@watkins-home.com] 
>Sent: Friday, May 21, 2004 10:00 AM
>To: 'Clemens Schwaighofer'; 'Dominik Sennfelder'
>Cc: 'linux-raid@vger.kernel.org'
>Subject: RE: Raid Failed What to to
>
>If you re-make the array with the same parameters as it has now the data
>will not be lost (assuming it is still there now).  If 1 disk is really bad
>then leave it out.
>
>The procedures depend on which program you use to create the array.  Do you
>use mkraid or mdadm?
>
>Guy
>
>-----Original Message-----
>From: linux-raid-owner@vger.kernel.org
>[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Clemens Schwaighofer
>Sent: Friday, May 21, 2004 4:45 AM
>To: Dominik Sennfelder
>Cc: linux-raid@vger.kernel.org
>Subject: Re: Raid Failed What to to
>
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>Hash: SHA1
>
>Dominik Sennfelder wrote:
>| Hello
>|
>| I have got a Raid 5 with 4 160 GB Disk,
>| On of the Disks Failed because. But I know its OK I had this for some
>| times.
>| A Restart solved The Problem.
>| But now  Tried to raidhotremove the Drive and removed the wrong drive.
>| I just recongized the Problem after i raidhotadded itagain.
>| No the Raid tries to sync again.
>
>well if you removed two drives from your Raid5 array, it might got
>competly out of sync and then there is no way to recover. I have never
>tried this with my raid, but if you add another disk it well be
>re-synced, ergo it tries to rebuild the array out of the CRCs on the
>other drives, if you remove two, you don't have enough redudant data to
>do this (raid 6 can recover from a 2 drive failure).
>
>I hope you have a backup.
>
>- --
>Clemens Schwaighofer - IT Engineer & System Administration
>==========================================================
>TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
>Tel: +81-(0)3-3545-7703            Fax: +81-(0)3-3545-7343
>http://www.tequila.co.jp
>==========================================================
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Raid Failed What to to

[Dominik Sennfelder]

Hello

I have got a Raid 5 with 4 160 GB Disk,
On of the Disks Failed because. But I know its OK I had this for some times.
A Restart solved The Problem.
But now  Tried to raidhotremove the Drive and removed the wrong drive.
I just recongized the Problem after i raidhotadded itagain.
No the Raid tries to sync again.
Syslog gets flooded by the following

May 20 23:52:25 utgard kernel: md: syncing RAID array md0
May 20 23:52:25 utgard kernel: md: minimum _guaranteed_ reconstruction 
speed: 1000 KB/sec/disc.
May 20 23:52:25 utgard kernel: md: using maximum available idle IO 
bandwith (but not more than 200000 KB/sec) for reconstruction.
May 20 23:52:25 utgard kernel: md: using 128k window, over a total of 
156288256 blocks.
May 20 23:52:25 utgard kernel: md: md0: sync done.

a cat /proc/mdstat gibes me different output

utgard:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid5]
md1 : active raid1 hdd2[1] hdc2[0]
      79055744 blocks [2/2] [UU]
     
md0 : active raid5 hdk1[4] hdi1[3] hdg1[5](F) hde1[0]
      468864768 blocks level 5, 32k chunk, algorithm 2 [4/2] [U__U]
      [>....................]  recovery =  0.0% (128/156288256) 
finish=13024.0min speed=128K/sec
unused devices: <none>
utgard:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid5]
md1 : active raid1 hdd2[1] hdc2[0]
      79055744 blocks [2/2] [UU]
     
md0 : active raid5 hdk1[4] hdi1[3] hdg1[5](F) hde1[0]
      468864768 blocks level 5, 32k chunk, algorithm 2 [4/2] [U__U]
      [>....................]  recovery =  0.0% (128/156288256) 
finish=13024.0min speed=128K/sec
unused devices: <none>
utgard:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid5]
md1 : active raid1 hdd2[1] hdc2[0]
      79055744 blocks [2/2] [UU]
     
md0 : active raid5 hdk1[4] hdi1[3] hdg1[5](F) hde1[0]
      468864768 blocks level 5, 32k chunk, algorithm 2 [4/2] [U__U]
     
unused devices: <none>
utgard:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid5]
md1 : active raid1 hdd2[1] hdc2[0]
      79055744 blocks [2/2] [UU]
     
md0 : active raid5 hdk1[4] hdi1[3] hdg1[5](F) hde1[0]
      468864768 blocks level 5, 32k chunk, algorithm 2 [4/2] [U__U]
     
unused devices: <none>

I know that all 4 Dives should be ok, how can i recover the Raid without 
loosing data?
Does a restart help?

Thanks buliwyf

Re: Raid Failed What to to

[Clemens Schwaighofer]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Dominik Sennfelder wrote:
| Hello
|
| I have got a Raid 5 with 4 160 GB Disk,
| On of the Disks Failed because. But I know its OK I had this for some
| times.
| A Restart solved The Problem.
| But now  Tried to raidhotremove the Drive and removed the wrong drive.
| I just recongized the Problem after i raidhotadded itagain.
| No the Raid tries to sync again.

well if you removed two drives from your Raid5 array, it might got
competly out of sync and then there is no way to recover. I have never
tried this with my raid, but if you add another disk it well be
re-synced, ergo it tries to rebuild the array out of the CRCs on the
other drives, if you remove two, you don't have enough redudant data to
do this (raid 6 can recover from a 2 drive failure).

I hope you have a backup.

- --
Clemens Schwaighofer - IT Engineer & System Administration
==========================================================
TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
Tel: +81-(0)3-3545-7703            Fax: +81-(0)3-3545-7343
http://www.tequila.co.jp
==========================================================
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RE: Raid Failed What to to

[Guy]

If you re-make the array with the same parameters as it has now the data
will not be lost (assuming it is still there now).  If 1 disk is really bad
then leave it out.

The procedures depend on which program you use to create the array.  Do you
use mkraid or mdadm?

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Clemens Schwaighofer
Sent: Friday, May 21, 2004 4:45 AM
To: Dominik Sennfelder
Cc: linux-raid@vger.kernel.org
Subject: Re: Raid Failed What to to

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Dominik Sennfelder wrote:
| Hello
|
| I have got a Raid 5 with 4 160 GB Disk,
| On of the Disks Failed because. But I know its OK I had this for some
| times.
| A Restart solved The Problem.
| But now  Tried to raidhotremove the Drive and removed the wrong drive.
| I just recongized the Problem after i raidhotadded itagain.
| No the Raid tries to sync again.

well if you removed two drives from your Raid5 array, it might got
competly out of sync and then there is no way to recover. I have never
tried this with my raid, but if you add another disk it well be
re-synced, ergo it tries to rebuild the array out of the CRCs on the
other drives, if you remove two, you don't have enough redudant data to
do this (raid 6 can recover from a 2 drive failure).

I hope you have a backup.

- --
Clemens Schwaighofer - IT Engineer & System Administration
==========================================================
TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
Tel: +81-(0)3-3545-7703            Fax: +81-(0)3-3545-7343
http://www.tequila.co.jp
==========================================================
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=5uyj
-----END PGP SIGNATURE-----
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