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 jail + zfs
Author: tld 
Date:   25-08-08 12:49

Hi,

ezjail isn't the fun way to play with jails. ZFS is.

First of all, the /etc/rc.d/jail script has been quite updated, and will take care of the day-to-day stuff, such as starting and stopping jails.

Simply define:

jail_enable="YES"
jail_list="psql"
jail_psql_rootdir="/usr/local/jails/psql.freebsddiary.org"
jail_psql_hostname="psql.freebsddiary.org"
jail_psql_ip="10.10.10.10"
jail_psql_devfs_enable="YES"
jail_psql_devfs_ruleset="devfsrules_jail" # devfs ruleset to apply to jail

And you can do:

/etc/rc.d/jail start psql

That's it. No need for a port to retrofit this.

Also, for the fun part. If you throw in ZFS in the loop, you get better control over disk usage (pr. jail or even pr. dir quotas, compression, redundancy-levels etc).

You can also snapshot jails.

That's right. If you're going to upgrade a jailed "machine", just snapshot it, test it, and roll back if there's a problem. If you have read-write userdata, simply put it in a separate zfs, and you can do it with parts of the "virtual machine".

But wait! There's more!

If you can create a base config, with most of the things you'll typically need for a jail, you can then snapshot and clone it.

If you have a base jail, and you'd like to install a 4MB package in addition to your standard stuff, the entire jail will only take up that 4MB of space.

You save RAM too. I think. Not entirely sure how ZFS fits into the FreeBSD page system, but since you're running your libc and whatnot from the same disk pages for all your jails, I'd think it's quite likely you'll save up some RAM too.

Sounds like a good plan?

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 Topics Author  Date
 jail + zfs   new
tld 25-08-08 12:49 
 Re: jail + zfs   new
Dan 25-08-08 13:44 
 Re: jail + zfs   new
tld 26-08-08 08:50 


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