Gentoo host, non-identical guests: 9p sharing portage dirs

[1clue]

Hi,

I have 2 KVM hosts. I want to allow Gentoo guests to borrow the necessary portage directories via 9p sharing.

The hosts are NOT identical hardware and will not be sharing VMs.

The guests will NOT be identical to the host. I'd like to make all common directories be shared read-only via 9p, and all others be individual to the guest.

Can somebody give me an outline of what needs to be where?

Here's what I think:

1. /etc/portage is specific to each install.
   
2. /usr/portage can be safely shared.
   
3. /tmp and /var/tmp are tmpfs
   

Is there anything else I need to worry about?

Is what I have correct?

Thanks.

[szatox]

Shared /usr/portage is safe, even when all machines access it at the same time.
9p provides you an ability to share host's directory with the guest, but you have 2 hosts so you will likely need 2 copies of /usr/portage. That is, unless you have some shared storage or are willing to share it over NFS too, and if you did, you'd probably be better skipping the 9p part and going for NFS only. So, with 9p keep /usr/portage at the host, and keep temporary files at each target. Building locally (From target's perspective), it's safe. Building on a share tmpfs should be safe as well thanks to locks emerge creates, though it differs more from "standard", standalone gentoo.

[1clue]

I guess I was unclear. I intend to have each host contain its /usr/portage and then use 9p within that host's VMs.

Are there any other biggies that can be shared across multiple non-identical images?

Thanks.

[Ant P.]

distfiles seems like an obvious one, you may be able to share /usr/src/linux as well.

[1clue]

Yes, I was just going to compile all the kernels on the host for that one. Easier comparing configs that way.

Thanks.