[CentOS] Re: Building software RAID mdmad adding a second disk
israel.garcia at cimex.com.cu
israel.garcia at cimex.com.cu
Thu Apr 13 13:29:32 UTC 2006
Thanks Alexandar for your soon answer, BUT, is there another easier way
to do this?
Regards,
Israel
>>Quoting israel.garcia at cimex.com.cu:
> >>How can I build a RAID 1 of all my particions of sda using mdadm?
>>1. Boot into rescue mode.
>>2. Shrink each file system a bit. Generally you'll use resize2fs
>>utility. MD uses some space at the end of partition for its metadata,
>>and you don't want this to overwrite the end of your filesystem. Most
>>HOWTOs on the net list this as one of the last steps (after mirrors
are
>>created). However if you do this as last step, in rare cases it may
>>lead to data loss. You probably want to be on the safe side and
shrink
>>file systems first (this will insure your data is secure). I'm not
>>sure by how much you need to shrink, should be somewhere in
>>documentation how many sectors at end of partition MD uses for
>>metadata...
>>3. Create mirror(s) using mdadm. Create using only one real partition
>>and use "missing" instead of second partition (wish Anaconda installer
>>would allow for something like this). Then use mdadm to add second
>>partition to the mirror. Something like:
>># mdadm --create /dev/md0 --run --level=1 --raid-devices=2 /dev/sda1
>>missing
>># mdadm /dev/md0 -a /dev/sdb1
>>4. Edit /etc/fstab file.
>>5. You'll need to rebuild initrd image(s) for installed kernel(s).
>>Just mount your filesystems somewhere, chroot into it and run
mkinitrd.
>> Mkinitrd should be smart enough to figure it'll need md device
>>drivers by looking into fstab file. Use -v option to mkinitrd to make
>>sure it included needed drivers into new initrd image.
>>6. Configure boot loader (LILO or Grub, whicever you use) to reflect
>>changes. Make sure you install boot loader into MBR of both drives.
>>--
>>See Ya' later, alligator!
>>http://www.8-P.ca/
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