Re: CVS commit: src/etc

[Brad Spencer <brad%anduin.eldar.org@localhost>]

Alexander Nasonov <alnsn%yandex.ru@localhost> writes:

> Brad Spencer wrote:
>> Alexander Nasonov <alnsn%yandex.ru@localhost> writes:
>> > Are there any downside of mixing legacy and non-legacy mountpoints?
>> > E.g. if my /var is legacy but /var/crash is a normal ZFS mountpoint?
>> 
>> That should work fine as long as /var was arranged to be mounted first.
>> The other way around may and probably is trouble right now, where a
>> zpool Not-legacy needs to be mounted so that a ZFS legacy filesystem or,
>> in fact, any other filesystem type gets mounted under it.  I believe
>> that Solaris did and probably still does have this problem too.  Legacy
>> ZFS mounts should be perfectly workable even from single user when /usr
>> isn't available yet for most simple use cases.
>
> Since I plan to migrate my ZFS setup to a smaller cgd disk, I gave
> legacy mountpoints a try to see how much complexity they add.
>
> I have the following ZFS mountpoints in my setup
>
> /usr      - legacy
> /var      - legacy
> /var/log  - legacy
> /var/tmp  - normal
> /var/mail - normal
> ...
>
> Ideally, I'd like to keep all datasets under one root:
>
> tank/base/usr      - legacy
> tank/base/var      - legacy
> tank/base/var/log  - legacy
> tank/base/var/mail - normal
>
> but it has a small inconvenience: every time I add a new dataset under
> a legacy mountpoint (e.g. create a dataset for /var/spool), it can't
> inherit a mountpoint from a legacy mountpoint and I have to set it
> manually (zfs set mountpoint=/var/spool tank/base/var/spool).

Yes, that would very much be the case.  Legacy mounts in ZFS are mostly
there to make /etc/fstab (and simular ilk) work the same as one may be
used to doing, so no inheritance.  You do not have to use most of the
zpool / zfs commands to get them mounted, but at the same time you can
set their sizes and such.  Getting too complicated with them, however,
may introduce unexpected adventure.

> One way to avoid this issue is to have separate hierarchies:
>
> tank/legacy
> tank/legacy/usr
> tank/legacy/var
> tank/legacy/var/log
> tank/base
> tank/base/var
> tank/base/var/mail
>
> but I'm pretty sure it has some downsides too.
>
> Alex


-- 
Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org