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Hi all!
I'm making a text mode installation of CentOS 5.5 on a single disk on which I intend to put a software RAID-1 degraded, thinking of adding another disk later on.
But if I try to make the installation in a RAID-1 with a single disk, the system does not allow it. There is any way to do it?
Thanks in advance for your replies.
Regards, Daniel
Daniel Bareiro wrote:
I'm making a text mode installation of CentOS 5.5 on a single disk on which I intend to put a software RAID-1 degraded, thinking of adding another disk later on.
But if I try to make the installation in a RAID-1 with a single disk, the system does not allow it. There is any way to do it?
Um, RAID-1 is mirroring. How can it create a mirror if there's nothing to mirror *to*?
mark
On 8/19/2010 3:54 PM, m.roth@5-cent.us wrote:
Daniel Bareiro wrote:
I'm making a text mode installation of CentOS 5.5 on a single disk on which I intend to put a software RAID-1 degraded, thinking of adding another disk later on.
But if I try to make the installation in a RAID-1 with a single disk, the system does not allow it. There is any way to do it?
Um, RAID-1 is mirroring. How can it create a mirror if there's nothing to mirror *to*?
mdadm create allows you to specify a device as "missing", and mirrors run fine that way, but I don't know how you get the installer to do it. The SME server distro (a modified Centos) does that by default if you only have one disk when you install so you can easily convert to raid later - and it makes a lot of sense.
On 08/19/2010 09:54 PM, m.roth@5-cent.us wrote:
Um, RAID-1 is mirroring. How can it create a mirror if there's nothing to mirror *to*?
upto CentOS-5 the installer will create a raid-1 with sync-delayed set, which allows the installer to finish the install and reboot fairly quickly. It does however create some interesting situations if one was to lose a disk soon after install, and if it was the first member of the setup :)
good news is that this function is now gone in newer anaconda's. so installing with 2x2TiB disks is expected to take between 3 to 3.5 hrs.
- KB
At Thu, 19 Aug 2010 20:55:22 +0000 CentOS mailing list centos@centos.org wrote:
But if I try to make the installation in a RAID-1 with a single disk, the system does not allow it. There is any way to do it?
Drop into a shell, create (force) the md devices, partition etc then drop into the installer and go...
Eg: Ctrl-Alt-F2 will get you a shell. Manually create the RAID set (but with only one disk). That is, use fdisk to partition the disk. It is important to set the partition types to Linux RAID auto-detect -- the kernel needs this to start the RAID early in the boot process. You'll want two partitions: a small one for /boot, and the rest for a LVM volume group (to be broken up into /, /home, swap, etc.). Once the RAID sets are up and running, use Ctrl-Alt-F1 to get back to the installer. You'll want to be sure to go back far enough in the process, so that going forward will get you to where the RAID-1 / LVM volumn group will be picked up. You can then set up the file systems you need, etc.
Later, when you get the second disk, you can use sfdisk to 'dup' the partitioning onto the new disk ('sfdisk -d /dev/sda|sfdisk /dev/sdb') , then use mdadm to add the partitions to the RAID arrays.
CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
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El jueves 19 de agosto del 2010 a las 19:41:09 -0300, Robert Heller escribió:
But if I try to make the installation in a RAID-1 with a single disk, the system does not allow it. There is any way to do it?
Drop into a shell, create (force) the md devices, partition etc then drop into the installer and go...
Eg: Ctrl-Alt-F2 will get you a shell. Manually create the RAID set (but with only one disk). That is, use fdisk to partition the disk. It is important to set the partition types to Linux RAID auto-detect -- the kernel needs this to start the RAID early in the boot process. You'll want two partitions: a small one for /boot, and the rest for a LVM volume group (to be broken up into /, /home, swap, etc.). Once the RAID sets are up and running, use Ctrl-Alt-F1 to get back to the installer. You'll want to be sure to go back far enough in the process, so that going forward will get you to where the RAID-1 / LVM volumn group will be picked up. You can then set up the file systems you need, etc.
Later, when you get the second disk, you can use sfdisk to 'dup' the partitioning onto the new disk ('sfdisk -d /dev/sda|sfdisk /dev/sdb'), then use mdadm to add the partitions to the RAID arrays.
I tested this by switching to a console from the installer in text mode. Despite I specified in the installer that the partitions were of type 'fd'. According to what I was checking after to switching to the console, the installer did not make the corresponding changes in the partitions so I had to manually make changes with fdisk. Then I created md devices making second member is 'missed'.
But to return to the partitioner of the installer in text mode, this did not take the changes. Even going a step back and choosing a custom design, I can not see the md devices created through the console.
Have I to perform some additional operations to take the changes in the installer?
Thanks for your replies.
Regards, Daniel
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Daniel Bareiro -
Joseph L. Casale -
Karanbir Singh -
Les Mikesell -
m.roth＠5-cent.us -
Robert Heller