CentOS - Feb 2015 - CentOS 7 : create RAID arrays manually using mdadm --create ?

Le 10/02/2015 02:01, Chris Murphy a ?crit :
> It's useful to know what layout you want. The installer will neither
> create, nor let you use, what it thinks are ill-advised layouts. The
> main reason I can think of for pre-creating md devices is to use a
> non-default chunk/strip size.
I'd like to be able to create either a simple RAID 1 layout with two 
disks, with a separate /boot partition, or a simple RAID 5 layout with 4 
disks, with a separate /boot partition too.

The layouts are described in this little Slackware-based HOWTO I wrote, 
and which I'm using on my servers. It's in French, but the command-line 
bits are universal :o)

http://www.microlinux.fr/slackware/Linux-HOWTOs/LAN-Server-HOWTO.txt

Cheers,

Niki

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On Mon, Feb 9, 2015 at 11:57 PM, Niki Kovacs <info at microlinux.fr>
wrote:
> I'd like to be able to create either a simple RAID 1 layout with two
disks,
> with a separate /boot partition, or a simple RAID 5 layout with 4 disks,
> with a separate /boot partition too.
The installer can create either of these layouts in manual partitioning.

>
> The layouts are described in this little Slackware-based HOWTO I wrote, and
> which I'm using on my servers. It's in French, but the command-line
bits are
> universal :o)
>
> http://www.microlinux.fr/slackware/Linux-HOWTOs/LAN-Server-HOWTO.txt
This can also be exactly reproduced with the installer using manual
partitioning. However:

- I'd substitute ext4 or xfs for /boot instead of ext2
- I'd make /boot bigger than 100MB which is almost certainly too small
to hold 3 kernels and initramfs's.
- I would not put swap on an md device, I'd just put a plain swap
partition on each device; first create two swap mountpoints, by
default this creates two swaps on one device. Select one of them and
click on the screwdriver+wrench icon (configure selected mountpoint),
and choose a specific drive, click select, then click Update Settings.
Repeat for each additional swap, making sure each is on its own drive.


-- 
Chris Murphy

On Tue, Feb 10, 2015 at 1:54 PM, Chris Murphy <lists at colorremedies.com>
wrote:
>
> - I would not put swap on an md device, I'd just put a plain swap
> partition on each device; first create two swap mountpoints,
If one of the devices fails, doesn't that mean that any processes with
swap on the associated space will be killed?    Avoiding that is kind
of the point of having mirrors....

-- 
   Les Mikesell
     lesmikesell at gmail.com