Re: Software raid, booting and bios

[Paul van der Vlis <paul@vandervlis.nl>]

Op 20-05-11 21:13, Ed W schreef:
> On 20/05/2011 09:33, Paul van der Vlis wrote:
>> You can select the "boot device priority" where you can choose about
>> devices types (DVD, harddisk, USB, network) but you can choose only one
>> SATA disk. Study it, and you will see I am right. I've asked it to my
>> rackserver-vendor, they say: "that's always the case".
> 
> Hi, what I have done with all my supermicro servers is to buy a tiny USB
> flash drive (physically small, not capacity small) - I think what I
> bought might be one of the tiny PNY devices, not sure though
> 
> The Supermicro boards have internal USB headers mounted on the
> motherboard, even with a 1U server I have plenty of room to install my
> USB on the MB (could stick them out the back of the server and cable tie
> them (or superglue them))

Nice to hear.

> Then I put SysrescueCD on my stick and setup GRUB with a bunch of boot
> options.
> 
> In my case I'm under the possibly misguided apprehension that my boot
> will fail over to the spare disks if one fails. However, I can set the
> subsequent failover to be my USB stick also.  I think I have them set at
> the moment that the USB stick boots the main drives as normal, but has a
> boot menu where I can also boot the sysrescueimage if I need to (I use
> this (over IPMI) for initial system installation and serious
> maintenance, eg failed grub upgrade or similar).

Interesting.

> The only other option that I think the big hosting guys use is to have a
> netboot setup which boots everything and can also offer rescue images,
> etc.  Beyond my skills to setup for my meagre number of servers, but if
> you have more than a couple of machines this could be a very good solution?

I don't have much machines, but I have my own IPv4 range.
So it is possible.

> For my needs the USB stick option is perfect

I will think about it. A little disadvantage is that it's not so easy to
have access to the USB stick maybe (you have to open the machine).

> Sysrescuecd suits me because all my servers are gentoo based - clearly
> it will work for other distros also, but you might want to evaluate
> other rescue distros before choosing one?

I use Debian, so I think I would choose a Debian-based rescue system.

What still a question is for me:
Is it better to put /boot on such an usb-stick or only the MBR?

Grub2 can boot from lvm/raid, and when I would have /boot on disk I can
have an MBR on disks too (for the case the usb stick would fail).
But difficult for me to understand that things like the initrd comes
from a software raid....

Another way would be make a /boot on a raid1 with 3 devices: the
harddisks and the USB stick.

With regards,
Paul van der Vlis.

-- 
http://www.vandervlis.nl/