software raid drive failed, please provide step bu steptorebuild

Jeff Vian jvian10 at charter.net
Sat Jul 29 01:12:49 UTC 2006


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 at charter.net>
> To: "For users of Fedora Core releases" <fedora-list at redhat.com>
> 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 at 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 at charter.net>
> >> To: "For users of Fedora Core releases" <fedora-list at redhat.com>
> >> 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 at redhat.com
> >> > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
> >>
> >
> > -- 
> > fedora-list mailing list
> > fedora-list at redhat.com
> > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
> > 
> 




More information about the users mailing list