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@xxxxxxxxxxx>
> To: "For users of Fedora Core releases" <fedora-list@xxxxxxxxxx>
> 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?
> > >
> >
> > --
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>
