Increasing Space in Software Raid

[John J. Culkin]

If I have 2 disk in a software raid, should I use "dd"  to make sure 
that they have the same Master Boot Record?

-- John C.

Broekman, Maarten wrote:
> If the disks are hotswap capable, you won't need a restart.  If the
> disks are not hotswap capable, then you'll need to shut down the system
> to replace them.
>
> The best thing would be to recreate the partitions exactly the same on
> the new disks first to make sure everything is still working fine.  Then
> increase the size of the partitions through fdisk and expand the
> filesystem with resize2fs.
>
> Maarten Broekman
>
> -----Original Message-----
> From: redhat-list-bounces at redhat.com
> [mailto:redhat-list-bounces at redhat.com] On Behalf Of John J. Culkin
> Sent: Wednesday, January 30, 2008 10:44 AM
> To: General Red Hat Linux discussion list
> Subject: Re: Increasing Space in Software Raid
>
> Thanks for the replys
>
> Isn't it a little more complicated then that. I would have to make 
> partitions on the new device and then I would have to expand then later
>
> Let me see if I can get a little Betty Crocker recipe here so that we 
> are all on the same page
>
> #Fail on device
> mdadm --fail /dev/sda1
> #Remove the failed drive and then replace it with a larger disk
> # mount the disk and format it (would I need a restart in there?)
> # Here is where it gets a little tricky for me
> # I think I need to make matching partitions on the larger device so 
> that I can bring it into the RAIDs (one for /boot, one for / root)
> #once that is rebuild I will break the raid again so that I can remove 
> the remaining smaller disk
> #I will then insert the new disk and mout and formate it
> # before I bring the new disk into the raid I will want to grow the size
>
> of the / root raid - this will also mean that I will have to grow its 
> partition - any tips on that?
>
> Am I missing anything?
>
> -- John C.
>
> Broekman, Maarten wrote:
>   
>> The easiest way would be to break the mirror. Replace the non-live
>> device with the new drive.  Make a new metadevice with the new device.
>> Copy the data.  Remove the last old device and put in the second new
>> device.  Then re-mirror.
>>
>> To make life easier you might want to use LVM also rather than raw
>> metadevices on the new devices.
>>
>> Maarten Broekman
>>
>> -----Original Message-----
>> From: redhat-list-bounces at redhat.com
>> [mailto:redhat-list-bounces at redhat.com] On Behalf Of
>> culkinj3 at scranton.edu
>> Sent: Tuesday, January 29, 2008 9:38 PM
>> To: redhat-list at redhat.com
>> Subject: Increasing Space in Software Raid
>>
>> Hello
>>
>> I have a server running RHEL 4 and it has a software Raid (1) of 2 250
>> gb Sata disks. I want to upgrade this to two 750 gb disks in a Raid 1
>> configuration. There is not another SATA slot available. 
>>
>> Here is some more information
>>
>> # df -ah
>> /dev/md1              229G  196G   21G  91% /
>> none                     0     0     0   -  /proc
>> none                     0     0     0   -  /sys
>> none                     0     0     0   -  /dev/pts
>> usbfs                    0     0     0   -  /proc/bus/usb
>> /dev/md0               99M   11M   83M  12% /boot
>> none                  505M     0  505M   0% /dev/shm
>> none                     0     0     0   -  /proc/sys/fs/binfmt_misc
>> automount(pid2042)       0     0     0   -  /var/autofs/bacula
>> /dev/sdc1             451G  340G   88G  80% /mnt/usb
>> #
>> cat /proc/mdstat
>> Personalities : [raid1]
>> md1 : active raid1 sda3[0]
>>       242983040 blocks [2/1] [U_]
>>
>> md0 : active raid1 sda1[0]
>>       104320 blocks [2/1] [U_]
>>
>> unused devices: <none>
>>
>>
>> # cat /etc/fstab
>> /dev/md1                /                       ext3    defaults
>> 1 1
>> /dev/md0                /boot                   ext3    defaults
>> 1 2
>> none                    /dev/pts                devpts  gid=5,mode=620
>> 0 0
>> none                    /dev/shm                tmpfs   defaults
>> 0 0
>> none                    /proc                   proc    defaults
>> 0 0
>> none                    /sys                    sysfs   defaults
>> 0 0
>> LABEL=SWAP-sdb2         swap                    swap    defaults
>> 0 0
>> LABEL=SWAP-sda2         swap                    swap    defaults
>> 0 0
>> /dev/sdc1               /mnt/usb                ext3    defaults
>> 0 0
>>
>>
>> Any suggestions/tips?
>>
>> -- John C.
>>
>>   
>>     
>
>   

-- 
John J. Culkin			Systems Administrator
John.Culkin at Scranton.edu	The University of Scranton
Phone: (570) 941-7665