software raid drive failed, please provide step bu step to rebuild

[Dan Carl]

I have/had a software raid running and sdc drive failed.
I got a replacement drive today and installed it.
My only experience with set partitions and raids in during initail setup.
I could not fdisk the new drive because i guess it wasn't reconized so I
rebooted.
Now I can reach the drive via fdisk but I have made more problems now (no
swap now)
and I'm not sure the steps to rebuild.
Background:
I have a FC3 with a software raid.
I have 3 SCSI 18gb hard drives
If I recall this how I set it up
md0 /boot 100MB raid 1 sda, sdb and sdc as spare
md1 /swp 768MB raid 0 sda, sdb, sdc
md2 / ext3 33GB raid 5 sda, sdb, sdc

Can someone please help?

[Sam Varshavchik]

Dan Carl writes:

>  I have/had a software raid running and sdc drive failed.
>  I got a replacement drive today and installed it.
>  My only experience with set partitions and raids in during initail setup.
>  I could not fdisk the new drive because i guess it wasn't reconized so I
>  rebooted.
>  Now I can reach the drive via fdisk but I have made more problems now (no
>  swap now)
>  and I'm not sure the steps to rebuild.
>  Background:
>  I have a FC3 with a software raid.
>  I have 3 SCSI 18gb hard drives
>  If I recall this how I set it up
>  md0 /boot 100MB raid 1 sda, sdb and sdc as spare
>  md1 /swp 768MB raid 0 sda, sdb, sdc
>  md2 / ext3 33GB raid 5 sda, sdb, sdc
>  
>  Can someone please help? 
Your first step is to determine your actual RAID configuration.  Unless you 
know exactly what belongs where, you're not going to get very far.

mdadm -Q -D /dev/md0

mdadm -Q -D /dev/md1

etc…

This will give you the information you need to map out how your existing 
drives are set up for RAID.

Your first step is to remove any failed devices, if mdadm -Q -D still shows 
any.  Use the mdadm -r option to remove any leftover failed devices.

Once your RAID layout consists of only the working partitions, you then need 
to figure out how your replacement drive will be added to your RAID 
configuration.  You'll need to figure out how it must be carved up into the 
different RAID partitions.  Use fdisk to partition your new disk, carefully 
making sure the sizes of the new partitions match EXACTLY the sizes of the 
corresponding partition in your existing RAID volumes.

Then, once you've double, and triple-checked your new partitions, use "mdadm 
-a" to add each partition to its appropriate RAID volume.  Linux will then 
automatically resync and rebuild your RAID volumes, one by one.

[Jeff Vian]

On Fri, 2006-07-28 at 16:29 -0500, Dan Carl wrote:
>  I have/had a software raid running and sdc drive failed.
>  I got a replacement drive today and installed it.
>  My only experience with set partitions and raids in during initail setup.
>  I could not fdisk the new drive because i guess it wasn't reconized so I
>  rebooted.
>  Now I can reach the drive via fdisk but I have made more problems now (no
>  swap now)
>  and I'm not sure the steps to rebuild.
>  Background:
>  I have a FC3 with a software raid.
>  I have 3 SCSI 18gb hard drives
>  If I recall this how I set it up
>  md0 /boot 100MB raid 1 sda, sdb and sdc as spare
>  md1 /swp 768MB raid 0 sda, sdb, sdc 
This toasted your /swp partition.
Raid 0 is striping, and a single failure toasts the entire device.

You would have been ahead with a non-raid swap, and had 3 separate
partitions, one on each device, for swap.  Failure of one would not have
toasted all. 


>  md2 / ext3 33GB raid 5 sda, sdb, sdc
>  
>  Can someone please help?
>

[Dan Carl]

I know its a raid 0 is a stripe.
Its my swap partition.
Why would I need fault tolerance on my swap.

Anyway,
I did what Sam suggested.
md0 is fine, md1 doesn't exist
mdadm -Q -D /dev/md2
it yeilded
/dev/md2:
        Version : 00.90.01
  Creation Time : Mon Feb 14 06:42:28 2005
     Raid Level : raid5
     Array Size : 34812416 (33.20 GiB 35.65 GB)
    Device Size : 17406208 (16.60 GiB 17.82 GB)
   Raid Devices : 3
  Total Devices : 2
Preferred Minor : 2
    Persistence : Superblock is persistent
Update Time : Fri Jul 28 17:56:25 2006
          State : clean, degraded
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0
Layout : left-symmetric
     Chunk Size : 256K
 Number   Major   Minor   RaidDevice State
       0       8        3        0      active sync   /dev/sda3
       1       8       19        1      active sync   /dev/sdb3
       2       0        0       -1      removed
           UUID : b4b161bc:2953b117:9c13c568:47693baa
         Events : 0.31307539

What if the  next step this is my mail server and I really don't have the
time to reload it.
I have my fstab, partition, mdstat,  infomation.
I ran this command sfdisk -d > sdb-parts.dump before a added the new drive.
Will any of this help?

Like I said before the only raid/partition experience I have is at initial
installation.



----- Original Message ----- 
From: "Jeff Vian" <jvian10(a)charter.net&gt;
To: "For users of Fedora Core releases" <fedora-list(a)redhat.com&gt;
Sent: Friday, July 28, 2006 5:44 PM
Subject: Re: software raid drive failed, please provide step bu step
torebuild


>  On Fri, 2006-07-28 at 16:29 -0500, Dan Carl wrote:
>  > I have/had a software raid running and sdc drive failed.
>  > I got a replacement drive today and installed it.
>  > My only experience with set partitions and raids in during initail 
setup.
>  > I could not fdisk the new drive because i guess it wasn't
> reconized so I
>  > rebooted.
>  > Now I can reach the drive via fdisk but I have made more problems now 
(no
>  > swap now)
>  > and I'm not sure the steps to rebuild.
>  > Background:
>  > I have a FC3 with a software raid.
>  > I have 3 SCSI 18gb hard drives
>  > If I recall this how I set it up
>  > md0 /boot 100MB raid 1 sda, sdb and sdc as spare
>  > md1 /swp 768MB raid 0 sda, sdb, sdc
>  This toasted your /swp partition.
>  Raid 0 is striping, and a single failure toasts the entire device.
>
>  You would have been ahead with a non-raid swap, and had 3 separate
>  partitions, one on each device, for swap.  Failure of one would not have
>  toasted all.
>
>
>  > md2 / ext3 33GB raid 5 sda, sdb, sdc
>  >
>  > Can someone please help?
>  >
>
>  -- 
>  fedora-list mailing list
>  fedora-list(a)redhat.com
>  To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list

[Jeff Vian]

On Fri, 2006-07-28 at 18:03 -0500, Dan Carl wrote:
>  I know its a raid 0 is a stripe.
>  Its my swap partition.
>  Why would I need fault tolerance on my swap.
>  
> From your first post below: 
        Now I can reach the drive via fdisk but I have
made more
        problems now (no swap now)
        and I'm not sure the steps to rebuild.
That is a good reason to make sure that vital disk partitions are not
made critically weak.  When striping across 3 drives the failure
probability is made 3X as likely and any single failure toasts the
entire device.

Since swap can use multiple partitions the likelyhood of failure and
total loss of swap space can be reduced by simply defining multiple swap
partitions without using striping.
        


>  Anyway,
>  I did what Sam suggested.
>  md0 is fine, md1 doesn't exist
>  mdadm -Q -D /dev/md2
>  it yeilded
>  /dev/md2:
>          Version : 00.90.01
>    Creation Time : Mon Feb 14 06:42:28 2005
>       Raid Level : raid5
>       Array Size : 34812416 (33.20 GiB 35.65 GB)
>      Device Size : 17406208 (16.60 GiB 17.82 GB)
>     Raid Devices : 3
>    Total Devices : 2
>  Preferred Minor : 2
>      Persistence : Superblock is persistent
>  Update Time : Fri Jul 28 17:56:25 2006
>            State : clean, degraded
>   Active Devices : 2
>  Working Devices : 2
>   Failed Devices : 0
>    Spare Devices : 0
>  Layout : left-symmetric
>       Chunk Size : 256K
>   Number   Major   Minor   RaidDevice State
>         0       8        3        0      active sync   /dev/sda3
>         1       8       19        1      active sync   /dev/sdb3
>         2       0        0       -1      removed
>             UUID : b4b161bc:2953b117:9c13c568:47693baa
>           Events : 0.31307539
>   
So mdadm -a needs to be used to add the 3rd device back to md2.  Sam's
instructions were clear on that.  For more information and education use
the man page for mdadm.


MANAGE MODE
       Usage: mdadm device options... devices...
       This usage will allow individual devices in  an  array  to  be
failed,
       removed  or  added.  It is possible to perform multiple
operations with
       one command. For example:
         mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1
       will firstly mark /dev/hda1 as faulty in /dev/md0 and will then
remove
       it  from the array and finally add it back in as a spare.
However only
       one md array can be affected by a single command.


I would do the following that you have not already stated done.
1. create the partition(s) on your new /dev/hdc
2. use mdadm as follows to add it to md2
     mdadm /dev/md2 -a /dev/sdc3
note that I assume your partitions are created and numbered as you have
already stated.

>  What if the  next step this is my mail server and I really don't
> have the
>  time to reload it.
>  I have my fstab, partition, mdstat,  infomation.
>  I ran this command sfdisk -d > sdb-parts.dump before a added the new drive.
>  Will any of this help?
>   
fdisk -l will list the partition information for each drive including
start and end cylinders such as this.

        [root@raptor pgsql]# fdisk -l /dev/hda
        
        Disk /dev/hda: 250.0 GB, 250059350016 bytes
        255 heads, 63 sectors/track, 30401 cylinders
        Units = cylinders of 16065 * 512 = 8225280 bytes
        
           Device Boot      Start         End      Blocks   Id  System
        /dev/hda1   *           1          21      168651   83  Linux
        /dev/hda2              22         532     4104607+  83  Linux
        /dev/hda3             533         721     1518142+  82  Linux
        swap
        /dev/hda4             722       30401   238404600    5  Extended
        /dev/hda5             722        1359     5124703+  83  Linux
        ....
        
> From that you can get not only the size of each partition, but the
actual cylinders used and can recreate the table on the new drive
appropriately with fdisk.
        
        
>  Like I said before the only raid/partition experience I have is at
> initial
>  installation.
>  
>  
>  
>  ----- Original Message ----- 
>  From: "Jeff Vian" <jvian10(a)charter.net&gt;
>  To: "For users of Fedora Core releases" <fedora-list(a)redhat.com&gt;
>  Sent: Friday, July 28, 2006 5:44 PM
>  Subject: Re: software raid drive failed, please provide step bu step
>  torebuild
>  
>  
>  > On Fri, 2006-07-28 at 16:29 -0500, Dan Carl wrote:
>  > > I have/had a software raid running and sdc drive failed.
>  > > I got a replacement drive today and installed it.
>  > > My only experience with set partitions and raids in during initail
>  setup.
>  > > I could not fdisk the new drive because i guess it wasn't reconized so I
>  > > rebooted.
>  > > Now I can reach the drive via fdisk but I have made more problems now
>  (no
>  > > swap now)
>  > > and I'm not sure the steps to rebuild.
>  > > Background:
>  > > I have a FC3 with a software raid.
>  > > I have 3 SCSI 18gb hard drives
>  > > If I recall this how I set it up
>  > > md0 /boot 100MB raid 1 sda, sdb and sdc as spare
>  > > md1 /swp 768MB raid 0 sda, sdb, sdc
>  > This toasted your /swp partition.
>  > Raid 0 is striping, and a single failure toasts the entire device.
>  >
>  > You would have been ahead with a non-raid swap, and had 3 separate
>  > partitions, one on each device, for swap.  Failure of one would not have
>  > toasted all.
>  >
>  >
>  > > md2 / ext3 33GB raid 5 sda, sdb, sdc
>  > >
>  > > Can someone please help?
>  > >
>  >
>  > -- 
>  > fedora-list mailing list
>  > fedora-list(a)redhat.com
>  > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
>

[Dan Carl]

Ok I totally see your point about striping my swap partition.
I read it some howto a few years back.

I did just what you said
I paritioned my new drive the exact same as the other two.
I issued the command
mdadm /dev/md2 -a /dev/sdc3
and the raid  md2 is rebuilding as I write this.

So how do I get setup my swap as you described?
Now I have three drives w/ partition
265072 sda2
265072 sdb2
265072 sdc2

Thank you soooo much
 Its 100 degrees, its Friday and now I have go outside and mow my lawn.
Look forward to reading your reply while sipping a cold one!


----- Original Message ----- 
From: "Jeff Vian" <jvian10(a)charter.net&gt;
To: "For users of Fedora Core releases" <fedora-list(a)redhat.com&gt;
Sent: Friday, July 28, 2006 6:48 PM
Subject: Re: software raid drive failed, please provide step bu 
steptorebuild


>  On Fri, 2006-07-28 at 18:03 -0500, Dan Carl wrote:
> > I know its a raid 0 is a stripe.
> > Its my swap partition.
> > Why would I need fault tolerance on my swap.
> >
> >From your first post below:
>         Now I can reach the drive via fdisk but I have made more
>         problems now (no swap now)
>         and I'm not sure the steps to rebuild.
>  That is a good reason to make sure that vital disk partitions are not
>  made critically weak.  When striping across 3 drives the failure
>  probability is made 3X as likely and any single failure toasts the
>  entire device.
>
>  Since swap can use multiple partitions the likelyhood of failure and
>  total loss of swap space can be reduced by simply defining multiple swap
>  partitions without using striping.
>
>
>
> > Anyway,
> > I did what Sam suggested.
> > md0 is fine, md1 doesn't exist
> > mdadm -Q -D /dev/md2
> > it yeilded
> > /dev/md2:
> >         Version : 00.90.01
> >   Creation Time : Mon Feb 14 06:42:28 2005
> >      Raid Level : raid5
> >      Array Size : 34812416 (33.20 GiB 35.65 GB)
> >     Device Size : 17406208 (16.60 GiB 17.82 GB)
> >    Raid Devices : 3
> >   Total Devices : 2
> > Preferred Minor : 2
> >     Persistence : Superblock is persistent
> > Update Time : Fri Jul 28 17:56:25 2006
> >           State : clean, degraded
> >  Active Devices : 2
> > Working Devices : 2
> >  Failed Devices : 0
> >   Spare Devices : 0
> > Layout : left-symmetric
> >      Chunk Size : 256K
> >  Number   Major   Minor   RaidDevice State
> >        0       8        3        0      active sync   /dev/sda3
> >        1       8       19        1      active sync   /dev/sdb3
> >        2       0        0       -1      removed
> >            UUID : b4b161bc:2953b117:9c13c568:47693baa
> >          Events : 0.31307539
> >
>  So mdadm -a needs to be used to add the 3rd device back to md2.  Sam's
>  instructions were clear on that.  For more information and education use
>  the man page for mdadm.
>
>
>  MANAGE MODE
>        Usage: mdadm device options... devices...
>        This usage will allow individual devices in  an  array  to  be
>  failed,
>        removed  or  added.  It is possible to perform multiple
>  operations with
>        one command. For example:
>          mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1
>        will firstly mark /dev/hda1 as faulty in /dev/md0 and will then
>  remove
>        it  from the array and finally add it back in as a spare.
>  However only
>        one md array can be affected by a single command.
>
>
>  I would do the following that you have not already stated done.
>  1. create the partition(s) on your new /dev/hdc
>  2. use mdadm as follows to add it to md2
>      mdadm /dev/md2 -a /dev/sdc3
>  note that I assume your partitions are created and numbered as you have
>  already stated.
>
> > What if the  next step this is my mail server and I really don't have the
> > time to reload it.
> > I have my fstab, partition, mdstat,  infomation.
> > I ran this command sfdisk -d > sdb-parts.dump before a added the new 
> > drive.
> > Will any of this help?
> >
>  fdisk -l will list the partition information for each drive including
>  start and end cylinders such as this.
>
>         [root@raptor pgsql]# fdisk -l /dev/hda
>
>         Disk /dev/hda: 250.0 GB, 250059350016 bytes
>         255 heads, 63 sectors/track, 30401 cylinders
>         Units = cylinders of 16065 * 512 = 8225280 bytes
>
>            Device Boot      Start         End      Blocks   Id  System
>         /dev/hda1   *           1          21      168651   83  Linux
>         /dev/hda2              22         532     4104607+  83  Linux
>         /dev/hda3             533         721     1518142+  82  Linux
>         swap
>         /dev/hda4             722       30401   238404600    5  Extended
>         /dev/hda5             722        1359     5124703+  83  Linux
>         ....
>
> >From that you can get not only the size of each partition, but the
>  actual cylinders used and can recreate the table on the new drive
>  appropriately with fdisk.
>
>
> > Like I said before the only raid/partition experience I have is at 
> > initial
> > installation.
> >
> >
> >
> > ----- Original Message ----- 
> > From: "Jeff Vian" <jvian10(a)charter.net&gt;
> > To: "For users of Fedora Core releases" <fedora-list(a)redhat.com&gt;
> > Sent: Friday, July 28, 2006 5:44 PM
> > Subject: Re: software raid drive failed, please provide step bu step
> > torebuild
> >
> >
> > > On Fri, 2006-07-28 at 16:29 -0500, Dan Carl wrote:
> > > > I have/had a software raid running and sdc drive failed.
> > > > I got a replacement drive today and installed it.
> > > > My only experience with set partitions and raids in during initail
> > setup.
> > > > I could not fdisk the new drive because i guess it wasn't reconized 
> > > > so I
> > > > rebooted.
> > > > Now I can reach the drive via fdisk but I have made more problems now
> > (no
> > > > swap now)
> > > > and I'm not sure the steps to rebuild.
> > > > Background:
> > > > I have a FC3 with a software raid.
> > > > I have 3 SCSI 18gb hard drives
> > > > If I recall this how I set it up
> > > > md0 /boot 100MB raid 1 sda, sdb and sdc as spare
> > > > md1 /swp 768MB raid 0 sda, sdb, sdc
> > > This toasted your /swp partition.
> > > Raid 0 is striping, and a single failure toasts the entire device.
> > >
> > > You would have been ahead with a non-raid swap, and had 3 separate
> > > partitions, one on each device, for swap.  Failure of one would not 
> > > have
> > > toasted all.
> > >
> > >
> > > > md2 / ext3 33GB raid 5 sda, sdb, sdc
> > > >
> > > > Can someone please help?
> > > >
> > >
> > > -- 
> > > fedora-list mailing list
> > > fedora-list(a)redhat.com
> > > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
> >
>
>  -- 
>  fedora-list mailing list
>  fedora-list(a)redhat.com
>  To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
>

[Jeff Vian]

On Fri, 2006-07-28 at 19:37 -0500, Dan Carl wrote:
>  Ok I totally see your point about striping my swap partition.
>  I read it some howto a few years back.
>  
>  I did just what you said
>  I paritioned my new drive the exact same as the other two.
>  I issued the command
>  mdadm /dev/md2 -a /dev/sdc3
>  and the raid  md2 is rebuilding as I write this.
>  
>  So how do I get setup my swap as you described?
>  Now I have three drives w/ partition
>  265072 sda2
>  265072 sdb2
>  265072 sdc2
>   
First format the swap partitions.  Note that fdisk  should list these as
type 82  Linux swap.
  
        mkswap /dev/sda2
        repeat for sdb2 and sdc2

then put into fstab the following
        /dev/sda2        swap           swap    defaults        0 0
        /dev/sdb2        swap           swap    defaults        0 0
        /dev/sdc2        swap           swap    defaults        0 0
        
Finally just issue the "swapon -a" command to enable swap as defined.

Now if one fails the remaining ones will continue to be used.

>  Thank you soooo much
>   Its 100 degrees, its Friday and now I have go outside and mow my lawn.
>  Look forward to reading your reply while sipping a cold one!
>  
>  
>  ----- Original Message ----- 
>  From: "Jeff Vian" <jvian10(a)charter.net&gt;
>  To: "For users of Fedora Core releases" <fedora-list(a)redhat.com&gt;
>  Sent: Friday, July 28, 2006 6:48 PM
>  Subject: Re: software raid drive failed, please provide step bu 
>  steptorebuild
>  
>  
>  > On Fri, 2006-07-28 at 18:03 -0500, Dan Carl wrote:
>  >> I know its a raid 0 is a stripe.
>  >> Its my swap partition.
>  >> Why would I need fault tolerance on my swap.
>  >>
>  >>From your first post below:
>  >        Now I can reach the drive via fdisk but I have made more
>  >        problems now (no swap now)
>  >        and I'm not sure the steps to rebuild.
>  > That is a good reason to make sure that vital disk partitions are not
>  > made critically weak.  When striping across 3 drives the failure
>  > probability is made 3X as likely and any single failure toasts the
>  > entire device.
>  >
>  > Since swap can use multiple partitions the likelyhood of failure and
>  > total loss of swap space can be reduced by simply defining multiple swap
>  > partitions without using striping.
>  >
>  >
>  >
>  >> Anyway,
>  >> I did what Sam suggested.
>  >> md0 is fine, md1 doesn't exist
>  >> mdadm -Q -D /dev/md2
>  >> it yeilded
>  >> /dev/md2:
>  >>         Version : 00.90.01
>  >>   Creation Time : Mon Feb 14 06:42:28 2005
>  >>      Raid Level : raid5
>  >>      Array Size : 34812416 (33.20 GiB 35.65 GB)
>  >>     Device Size : 17406208 (16.60 GiB 17.82 GB)
>  >>    Raid Devices : 3
>  >>   Total Devices : 2
>  >> Preferred Minor : 2
>  >>     Persistence : Superblock is persistent
>  >> Update Time : Fri Jul 28 17:56:25 2006
>  >>           State : clean, degraded
>  >>  Active Devices : 2
>  >> Working Devices : 2
>  >>  Failed Devices : 0
>  >>   Spare Devices : 0
>  >> Layout : left-symmetric
>  >>      Chunk Size : 256K
>  >>  Number   Major   Minor   RaidDevice State
>  >>        0       8        3        0      active sync   /dev/sda3
>  >>        1       8       19        1      active sync   /dev/sdb3
>  >>        2       0        0       -1      removed
>  >>            UUID : b4b161bc:2953b117:9c13c568:47693baa
>  >>          Events : 0.31307539
>  >>
>  > So mdadm -a needs to be used to add the 3rd device back to md2.  Sam's
>  > instructions were clear on that.  For more information and education use
>  > the man page for mdadm.
>  >
>  >
>  > MANAGE MODE
>  >       Usage: mdadm device options... devices...
>  >       This usage will allow individual devices in  an  array  to  be
>  > failed,
>  >       removed  or  added.  It is possible to perform multiple
>  > operations with
>  >       one command. For example:
>  >         mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1
>  >       will firstly mark /dev/hda1 as faulty in /dev/md0 and will then
>  > remove
>  >       it  from the array and finally add it back in as a spare.
>  > However only
>  >       one md array can be affected by a single command.
>  >
>  >
>  > I would do the following that you have not already stated done.
>  > 1. create the partition(s) on your new /dev/hdc
>  > 2. use mdadm as follows to add it to md2
>  >     mdadm /dev/md2 -a /dev/sdc3
>  > note that I assume your partitions are created and numbered as you have
>  > already stated.
>  >
>  >> What if the  next step this is my mail server and I really don't have the
>  >> time to reload it.
>  >> I have my fstab, partition, mdstat,  infomation.
>  >> I ran this command sfdisk -d > sdb-parts.dump before a added the new 
>  >> drive.
>  >> Will any of this help?
>  >>
>  > fdisk -l will list the partition information for each drive including
>  > start and end cylinders such as this.
>  >
>  >        [root@raptor pgsql]# fdisk -l /dev/hda
>  >
>  >        Disk /dev/hda: 250.0 GB, 250059350016 bytes
>  >        255 heads, 63 sectors/track, 30401 cylinders
>  >        Units = cylinders of 16065 * 512 = 8225280 bytes
>  >
>  >           Device Boot      Start         End      Blocks   Id  System
>  >        /dev/hda1   *           1          21      168651   83  Linux
>  >        /dev/hda2              22         532     4104607+  83  Linux
>  >        /dev/hda3             533         721     1518142+  82  Linux
>  >        swap
>  >        /dev/hda4             722       30401   238404600    5  Extended
>  >        /dev/hda5             722        1359     5124703+  83  Linux
>  >        ....
>  >
>  >>From that you can get not only the size of each partition, but the
>  > actual cylinders used and can recreate the table on the new drive
>  > appropriately with fdisk.
>  >
>  >
>  >> Like I said before the only raid/partition experience I have is at 
>  >> initial
>  >> installation.
>  >>
>  >>
>  >>
>  >> ----- Original Message ----- 
>  >> From: "Jeff Vian" <jvian10(a)charter.net&gt;
>  >> To: "For users of Fedora Core releases"
> <fedora-list(a)redhat.com&gt;
>  >> Sent: Friday, July 28, 2006 5:44 PM
>  >> Subject: Re: software raid drive failed, please provide step bu step
>  >> torebuild
>  >>
>  >>
>  >> > On Fri, 2006-07-28 at 16:29 -0500, Dan Carl wrote:
>  >> > > I have/had a software raid running and sdc drive failed.
>  >> > > I got a replacement drive today and installed it.
>  >> > > My only experience with set partitions and raids in during initail
>  >> setup.
>  >> > > I could not fdisk the new drive because i guess it wasn't
> reconized 
>  >> > > so I
>  >> > > rebooted.
>  >> > > Now I can reach the drive via fdisk but I have made more problems now
>  >> (no
>  >> > > swap now)
>  >> > > and I'm not sure the steps to rebuild.
>  >> > > Background:
>  >> > > I have a FC3 with a software raid.
>  >> > > I have 3 SCSI 18gb hard drives
>  >> > > If I recall this how I set it up
>  >> > > md0 /boot 100MB raid 1 sda, sdb and sdc as spare
>  >> > > md1 /swp 768MB raid 0 sda, sdb, sdc
>  >> > This toasted your /swp partition.
>  >> > Raid 0 is striping, and a single failure toasts the entire device.
>  >> >
>  >> > You would have been ahead with a non-raid swap, and had 3 separate
>  >> > partitions, one on each device, for swap.  Failure of one would not 
>  >> > have
>  >> > toasted all.
>  >> >
>  >> >
>  >> > > md2 / ext3 33GB raid 5 sda, sdb, sdc
>  >> > >
>  >> > > Can someone please help?
>  >> > >
>  >> >
>  >> > -- 
>  >> > fedora-list mailing list
>  >> > fedora-list(a)redhat.com
>  >> > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
>  >>
>  >
>  > -- 
>  > fedora-list mailing list
>  > fedora-list(a)redhat.com
>  > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
>  > 
>

[Les Mikesell]

On Fri, 2006-07-28 at 17:44 -0500, Jeff Vian wrote:

>  This toasted your /swp partition.
>  Raid 0 is striping, and a single failure toasts the entire device.
>  
>  You would have been ahead with a non-raid swap, and had 3 separate
>  partitions, one on each device, for swap.  Failure of one would not have
>  toasted all.  
Yes, but losing swap will kill any processes that happened to be
using it.  The results of continuing to run with unpredictable
things happening might be worse than crashing immediately.

--
  Les Mikesell
   lesmikesell(a)gmail.com

[Jeff Vian]

On Mon, 2006-07-31 at 10:54 -0500, Les Mikesell wrote:
>  On Fri, 2006-07-28 at 17:44 -0500, Jeff Vian wrote:
>  
>  > This toasted your /swp partition.
>  > Raid 0 is striping, and a single failure toasts the entire device.
>  > 
>  > You would have been ahead with a non-raid swap, and had 3 separate
>  > partitions, one on each device, for swap.  Failure of one would not have
>  > toasted all. 
>  
>  Yes, but losing swap will kill any processes that happened to be
>  using it.  The results of continuing to run with unpredictable
>  things happening might be worse than crashing immediately.
>   
I never said loss of a swap partition would not have consequences.
I said that by using multiple partitions for swap that losing one would
not totally lose the swap.  A reboot with one failed will continue to
use the remaining parts and at least part of the swap will be available.

>  --
>    Les Mikesell
>     lesmikesell(a)gmail.com
>  
>