zfs discuss - Dec 2005 - Interesting interaction on installserver.

After creating an install server on a ZFS filesystem, a nasty surprise
awaited me on the first boot of said server.

The standard /tftpboot/I86PC..... loopback mount which was added
to vfstab caused booting to fail because the ZFS filesystems aren''t
present when the "local" filesystems are mounted.  The loopback mount
failed and the server refused to come up.

I worked around this by making the loopback mount an autofs mount.

Casper

Hmmm, it looks like we currently do the following in fs-local:

	1. Mount all filesystems from /etc/vfstab
	2. Mount all ZFS filesystems

In general mixing layered /etc/vfstab and ZFS auto-managed mounts is a
bad idea.  We could switch the order of the above operations, but there
would be the potential for further bad interations (i.e. if /usr were
UFS, but /usr/local was ZFS).

The only supported method of mixing non-ZFS layered filesystems in
/etc/vfstab is to use legacy ZFS mounts, and place the ZFS filesystem in
/etc/vfstab before the loopback one.

- Eric

On Sat, Dec 31, 2005 at 03:34:53PM +0100, Casper.Dik at sun.com
wrote:
> 
> After creating an install server on a ZFS filesystem, a nasty surprise
> awaited me on the first boot of said server.
> 
> The standard /tftpboot/I86PC..... loopback mount which was added
> to vfstab caused booting to fail because the ZFS filesystems
aren''t
> present when the "local" filesystems are mounted.  The loopback
mount
> failed and the server refused to come up.
> 
> I worked around this by making the loopback mount an autofs mount.
> 
> Casper
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock

>Hmmm, it looks like we currently do the following in fs-local:
>
>	1. Mount all filesystems from /etc/vfstab
>	2. Mount all ZFS filesystems
>
>In general mixing layered /etc/vfstab and ZFS auto-managed mounts is a
>bad idea.  We could switch the order of the above operations, but there
>would be the potential for further bad interations (i.e. if /usr were
>UFS, but /usr/local was ZFS).
>
>The only supported method of mixing non-ZFS layered filesystems in
>/etc/vfstab is to use legacy ZFS mounts, and place the ZFS filesystem in
>/etc/vfstab before the loopback one.

It''s somewhat unfortunate that using supported commands like
"setup_install_server" and "add_install_client" creates this
situation.  That is something that needs to be addressed.

Casper

On Sat, Dec 31, 2005 at 05:33:31PM +0100, Casper.Dik at Sun.COM
wrote:
> 
> It''s somewhat unfortunate that using supported commands like
> "setup_install_server" and "add_install_client" creates
this
> situation.  That is something that needs to be addressed.
> 
Absolutely, there is a _huge_ amount of work that needs to be done in
the admin/install area around ZFS.  Install, upgrade, netinstall
servers, zones upgrade, and more.  We have folks looking into these
issues, I assure you that this is on their list.

In the meantime, it should probably be documented in the FAQ and admin
guide.

- Eric

--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock

Casper.Dik at Sun.COM wrote:
>
> After creating an install server on a ZFS filesystem, a nasty surprise
> awaited me on the first boot of said server.
>
> The standard /tftpboot/I86PC..... loopback mount which was added
> to vfstab caused booting to fail because the ZFS filesystems
aren''t
> present when the "local" filesystems are mounted.  The loopback
mount
> failed and the server refused to come up.
This could be solved by adding zfs (mount-point only) entries to vfstab 
(with no backing storage field) and this way telling the system what to mount 
when.

J?rg

-- 
 EMail:joerg at schily.isdn.cs.tu-berlin.de (home) J?rg Schilling D-13353 Berlin
       js at cs.tu-berlin.de		(uni)  
       schilling at fokus.fraunhofer.de	(work) Blog: http://schily.blogspot.com/
 URL:  http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily

Casper.Dik at Sun.COM wrote:
> It''s somewhat unfortunate that using supported commands like
> "setup_install_server" and "add_install_client" creates
this
> situation.  That is something that needs to be addressed.
Looks like a result of leaving the generic UNIX philosohy with the
way zfs mounts are handled. Maybe this should be rethought....

J?rg

-- 
 EMail:joerg at schily.isdn.cs.tu-berlin.de (home) J?rg Schilling D-13353 Berlin
       js at cs.tu-berlin.de		(uni)  
       schilling at fokus.fraunhofer.de	(work) Blog: http://schily.blogspot.com/
 URL:  http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily

Eric Schrock <eric.schrock at sun.com> wrote:
> On Sat, Dec 31, 2005 at 05:33:31PM +0100, Casper.Dik at Sun.COM wrote:
> > 
> > It''s somewhat unfortunate that using supported commands like
> > "setup_install_server" and "add_install_client"
creates this
> > situation.  That is something that needs to be addressed.
> > 
>
> Absolutely, there is a _huge_ amount of work that needs to be done in
> the admin/install area around ZFS.  Install, upgrade, netinstall
> servers, zones upgrade, and more.  We have folks looking into these
> issues, I assure you that this is on their list.
Maybe it is better to do less work by having zfs in /etc/vfstab again.
At least, you then will _know_ that there will be no unknown problems.

J?rg

-- 
 EMail:joerg at schily.isdn.cs.tu-berlin.de (home) J?rg Schilling D-13353 Berlin
       js at cs.tu-berlin.de		(uni)  
       schilling at fokus.fraunhofer.de	(work) Blog: http://schily.blogspot.com/
 URL:  http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily

On Wed, Jan 04, 2006 at 01:58:33PM +0100, Joerg Schilling
wrote:
> 
> Maybe it is better to do less work by having zfs in /etc/vfstab again.
> At least, you then will _know_ that there will be no unknown problems.
> 
You can have zfs filesystems in /etc/vfstab by using legacy mounts.
It''s just not the default, nor will it ever be.

- Eric

--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock

Eric Schrock <eric.schrock at sun.com> wrote:
> On Wed, Jan 04, 2006 at 01:58:33PM +0100, Joerg Schilling wrote:
> > 
> > Maybe it is better to do less work by having zfs in /etc/vfstab again.
> > At least, you then will _know_ that there will be no unknown problems.
> > 
>
> You can have zfs filesystems in /etc/vfstab by using legacy mounts.
> It''s just not the default, nor will it ever be.
If you find and fix all other problems caused by this change, it could stay as 
is.

J?rg

-- 
 EMail:joerg at schily.isdn.cs.tu-berlin.de (home) J?rg Schilling D-13353 Berlin
       js at cs.tu-berlin.de		(uni)  
       schilling at fokus.fraunhofer.de	(work) Blog: http://schily.blogspot.com/
 URL:  http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily