[vserver] Hashify Questions

From: Ted Barnes <madogdevelopment_at_gmail.com>
Date: Tue 18 Feb 2014 - 19:00:04 GMT
Message-ID: <5303ADB4.6060101@gmail.com>

Hi All:

I'm starting to explore "hashify", and have a number of questions
(sorry, this is long but am hoping to gain a good understanding if
possible). If there is a link that answers these, please let me know
(the links I've found are short and I'm unsure if they are "current")?
I'm running Wheezy host and guests, with Mate on the guests. Thanks!

1) Hashify advantages

Are the advantages of using hashified guests a) saving disk space and b)
performance (e.g., restarting a guest will be faster)?

2) Set up steps - are these the "current" right ones to use? Does the
error I get matter?

Per
"http://linux-vserver.org/Frequently_Asked_Questions#What_is_vhashify.3F",
I used the following steps.

On Host:

mkdir /etc/vservers/.defaults/apps/vunify/hash /vservers/.hash
ln -s /vservers/.hash /etc/vservers/.defaults/apps/vunify/hash/root

On Guest:

mkdir /etc/vservers/<vservername>/apps/vunify
vserver name-of-guest hashify

Note: when I run the hashify command, I get "Duplicate hash-dir entry
'00' found" which I do not believe prevents the hashify process from
completing, but should I worry about this message?

3) Cloning a hashified guest
- If I clone a hashified guest, should the cloning process go faster
than "regular" cloning, or should it be roughly the same?

- Are the cloning commands the same (e.g., vserver vserver5 build -m
clone --hostname vserver5.mydomain.com --interface eth0:192.168.1.14/24
-- --source /vservers/vserver4)?

- Once the cloning of a hashified guest is complete, is that clone
hashified? My take is "no" and I need to run the hashify command
against the new clone

- Is there command to show if a guest is hashified or not?

- Is there an "undo" short of going in and deleting links? I'm not sure
why I'd want this, but was curious.

4) If hashified guest were compromised...

If a hashfied guest were compromised with malware, and the attacker got
to root on the guest, would a reboot put the guest's system files back
in order? Or could the guest's hashified files still be compromised
(assuming the attacker had not seized control of the host)?

5) I intend to put /home in one Logical Volume, and put "/everything
else" in another logical volume. I assume at the end of the day I only
want to hashify the "/everthing else". Is that right? Given that the
"vserver guestname hashify" command appears to hashify the entire
vserver guest, is there a command alternative I could use?

6) Updates

My understanding is after updating each guest, I would need to
re-hashify them all - is that correct?

Again, apologize this is long - any help appreciated!
Received on Tue Feb 18 19:00:17 2014

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