Earth Computing

[Etienne Goyer]

Alvin wrote:
> I know. It's still the most useful filesystem around, and we want to
> use the best tools for the job. LVM is not as flexible as ZFS.

The main objection I have against ZFS is that it does not have any
recovery tool (or so I heard; correct me if I am wrong).  As such, I
would not trust it in production, but you may know something I don't.


>>>>   These run Jaunty because of the above bugs and because of a regression
>>>>   [bug
>>>>
>>>> 224138] "No NFS modules in karmic 32-bit"
>> Again, not trying to make excuse, and not sure I understand the problem
>> correctly, but that sounds like an overstatement.  It seems like the
>> -virtual kernel flavor is missing some modules (including those for
>> NFS*v4*), but you could just as well use the -generic or -server flavor.
>>  Or am I misunderstanding something?
> 
> Yes, virtio. The virtual kernels perform faster. In extreme cases, a 
> calculation could take as much as 6 hours. You will run in stability issues 
> when using the normal kernel. (Our old Solaris8 machines do the same in 6 
> days.)
> Besides, when the virtual machines were build, we had no choice due to this 
> bug: [kvm guests not using virtio for networking lose network connectivity]
> https://bugs.launchpad.net/bugs/286101

I do not know.  I have the 2.6.31-17-generic kernel running on karmic,
and it does have virtio compiled as a module.  I run all my KVM vm using
either the -generic or -server kernel flavour, and I have not had any
problem so far.  Are you sure you *have* to use the -virtual kernel?

Someone else can clarify, but I was under the impression the -virtual
flavour was being phased out.  Is that correct?


> Is LTSP not heavily dependant on NFS?

Yes, as the read-only root file system.  Security is not critical in
this use-case.


> I think it's a mistake to throw the Unix 
> way overboard in favour of MS Windows solutions. NFS and CIFS have different 
> usage scenarios.

CIFS has been an IETF standard draft for a long time (now expired).  It
is not Windows-specific anymore (and has not been for a while).  With
the advent of the Unix Extensions, it offer complete POSIX file system
semantic.  What more can you ask for?  :)


> There is certainly room for improvement, but that's why NFSv4 
> exists.

I am not experienced enough in NFSv4 to make an enlightened judgment,
but my feeling is that it is quite byzantine.  Beside the dependence on
Kerberos for authentication (which is perfectly fine, but rule it out in
many use-case), it still relies on a mish-mash of different RPC
mechanism for id mapping, locking, etc.  I could never wrap my head
around it.

That being said, Samba is anything but straightforward itself, and I am
not apologizing for it.


> Users need access to the same filesystems anyway. Of course they do make 
> mistakes and erase files, or move them to the wrong place. That's why the 
> regular ZFS snapshots can be so handy.

Just so you know, LVM can also do CoW snapshot (albeit, perhaps, less
elegantly than ZFS).


Best regards,

-- 
Etienne Goyer
Technical Account Manager - Canonical Ltd
Ubuntu Certified Instructor   -    LPIC-3

 ~= Ubuntu: Linux for Human Beings =~