Re: [gentoo-user] NFS tutorial for the brain dead sysadmin?

["J. Roeleveld" <joost@antarean.org>]

On Sunday, July 27, 2014 08:44:02 PM Kerin Millar wrote:
> On 27/07/2014 17:55, J. Roeleveld wrote:
> > On 27 July 2014 18:25:24 CEST, "Stefan G. Weichinger" <lists@xunil.at> 
wrote:
> >> Am 26.07.2014 04:47, schrieb walt:
> >>> So, why did the "broken" machine work normally for more than a year
> >>> without rpcbind until two days ago?  (I suppose because nfs-utils was
> >>> updated to 1.3.0 ?)
> >>> 
> >>> The real problem here is that I have no idea how NFS works, and each
> >>> new version is more complicated because the devs are solving problems
> >>> that I don't understand or even know about.
> >> 
> >> I double your search for understanding ... my various efforts to set up
> >> NFSv4 for sharing stuff in my LAN also lead to unstable behavior and
> >> frustration.
> >> 
> >> Only last week I re-attacked this topic as I start using puppet here to
> >> manage my systems ... and one part of this might be sharing
> >> /usr/portage
> >> via NFSv4. One client host mounts it without a problem, the thinkpads
> >> don't do so ... just another example ;-)
> >> 
> >> Additional in my context: using systemd ... so there are other
> >> (different?) dependencies at work and services started.
> >> 
> >> I'd be happy to get that working in a reliable way. I don't remember
> >> unstable behavior with NFS (v2 back then?) when we used it at a company
> >> I worked for in the 90s.
> >> 
> >> Stefan
> > 
> > I use NFS for filesharing between all wired systems at home.
> > Samba is only used for MS Windows and laptops.
> > 
> > Few things I always make sure are valid:
> > - One partition per NFS share
> > - No NFS share is mounted below another one
> > - I set the version to 3 on the clients
> > - I use LDAP for the user accounts to ensure the UIDs and GIDs are
> > consistent.
> These are generally good recommendations. I'd just like to make a few
> observations.
> 
> The problems associated with not observing the first constraint (one
> filesystem per export) can be alleviated by setting an explicit fsid.
> Doing so can also help to avoid stale handles on the client side if the
> backing filesystem changes - something that is very useful in a
> production environment. Therefore, I tend to start at 1 and increment
> with each newly added export. For example:-
> 
>    /export/foo      *(async,no_subtree_check,fsid=1)
>    /export/foo/bar  *(async,no_subtree_check,fsid=2)
>    /export/baz      *(async,no_subtree_check,fsid=3)
> 
> If using NFSv3, I'd recommend using "nolock" as a mount option unless
> there is a genuine requirement for locks to be co-ordinated. Such locks
> are only advisory and are of questionable value. Using nolock simplifies
> the requirements on both server and client side, and is beneficial for
> performance.
> 
> NFSv3/UDP seems to be limited to a maximum read/write block size of
> 32768 in Linux, which will be negotiated by default. Using TCP, the
> upper bound will be the value of /proc/fs/nfsd/max_block_size on the
> server. Its value may be set to 1048576 at the most. NFSv3/TCP is
> problematic so I would recommend NFSv4 if TCP is desired as a transport
> protocol.
> 
> NFSv4 provides a useful uid/gid mapping feature that is easier to set up
> and maintain than nss_ldap.
> 
> > NFS4 requires all the exports to be under a single foldertree.
> 
> This is a myth:
> http://linuxcostablanca.blogspot.co.uk/2012/02/nfsv4-myths-and-legends.html.
> Exports can be defined and consumed in the same manner as with NFSv3.

When I originally tried NFSv4, it refused to work unless they were all under 
the same directory.
As I dislike that, I decided against using it.

That was a long time ago, will revisit that part again later.

Interesting link, I wonder how difficult it will be to combine that with Samba 
4 and use the Samba AD structure for NFSv4 with either ZFS or BTRFS 
underneath.

--
Joost