[clug] Booting: Debian stable uses grub 1 or 2? recognising LVM's

[Scott Ferguson]

On 04/03/13 17:54, steve jenkin wrote:
> I'm setting up a new desktop soon, probably Debian stable.
> 
> Will fit two disks, an SSD and HDD. Part of my experimenting will be
> using an LVM module that spreads files across SSD/HDD based on the
> amount of (read?) access they get.

Difficult to understand the advantages of that... how big is this SSD??
While I can understand the advantages of faster read access for
/non-home files, why not just put them on the SSD??

> 
> I'm wondering how I should setup the SSD boot disk to minimise
> disruption as I test with the LVM.
> 
> Currently I'm thinking:
> * SSD: 1-2GB as ext2/3 boot filesystem

/boot holds a kernel, or maybe kernels if you're so inclined, as well as
GRUB. 1-2GB seems excessive (128M is more than most people will need for
a "desktop").

Personally I'd just use ext2 with noatime for the /boot partition

> * SSD: half remaining for normal system, possibly as a cache to the HDD
>        [flashcache?]
> * SSD: remaining as test area for LVM

You want a desktop, and you want to have a machine for testing?? :/

> * HDD: half as ext3

Consider ext4, it's performance is on par with XFS. Both prefer tuning.

> or xfs filesystem, half as test area for LVM
> 
> I'm much happier with grub-1 and its simple config file,

simple is not just a synonym of less complicated ;)

> but can setup
> and use grub-2 if I have to. I'm not sure what Debian stable provides (I
> expect both) or which comes as the default.

GRUB2 is the default with Squeeze. GRUB1 is no longer developed so don't
expect it to support many new things.

> 
> Though I'd like to throw all the SSD & HDD into a single LVM
> 
> My concern is how grub-1 and grub-2 handle LVM modules they've not seen
> before. Do I have to modify them to understand the new LVM or just have
> a boot partition with simple filesystem?

?

The "usual" process is:-
Boot from install image/CD/USB etc, select expert or expertgui, set up
LVM, partition, select at least basic software, install GRUB(2), finish
install.

Ignore the GRUB1 - it's possible (but has no advantages), but GRUB2 is
the default bootmanager for Squeeze, and it supports LVM better. Given
the above build process GRUB(2) doesn't have the "understand" the new LVM.



> 
> Anyone suggest what I should be researching and suitable search terms?

Start with http://www.debian.org/releases/stable/installmanual

Choosing stable (Squeeze) generally implies stability is what you are
after. So perhaps consider sticking to non-exotic setups.

> 
> Thanks in Advance
> 
> steve
> 
> 
> 


if it was me:-

SSD GPT
lvm0
primary primary /boot 128MB ext2 noatime
primary secondary /root (available space) ext4 noatime [*1]
primary tertiary /swap 500MB [*2]

HDD GPT
lvm1 (LUKS?)
primary primary /swap 500MB [*2]
primary secondary /home (half space) ext4 noatime (or xfs)
remaining space reserved for lvm snapshot


[*1]
If you know your requirements, and you will be running servers, then
probably better to separate /etc, /root, /usr /var etc instead a single
root partition.

[*2]
Really depends on how much system RAM you intend to have, and what
you'll be doing on your "desktop". Where possible I avoid swap, it's
"generally" not required. Unless you are working with very large images,
video editing, or 3D rendering and have little system RAM you won't need
more than 1GiB total swap (and swap is *slow* - it also slows down your
drives).

Logic - simplicity for ease of management, and putting what will best
leverage the SSD on the SSD.


Kind regards