zfs discuss - Dec 2006 - ZFS questions

I will have a file system in a SAN using ZFS.  Can someone answer my
questions?

1. Can I create  ZFS volumes on a ZFS file system from one server,
     attach the file system read-write to a different server (to load data),
     then detach the file system from that server and attach the file system
     read-only to multiple other servers?

2. Can I expand on the fly a ZFS volume within a file system when the
     file system it''s attached to a server read-write?

Thanks for your help,

Dave

On Thu, 14 Dec 2006, Dave Burleson wrote:
> 1. Can I create  ZFS volumes on a ZFS file system from one server,
>     attach the file system read-write to a different server (to load data),
>     then detach the file system from that server and attach the file system
>     read-only to multiple other servers?
If I understand you correctly, then yes, what you propose is possible
(even without ZFS), using NFS.  But one can''t remotely
"force" a server
to mount a file system; the file system has to be made available and
interested clients must mount it.  So:

	1. Make file system available (e.g., use share).

	2. Have the client mount it r/w so that it can load its data.

	3. have the other clients mount it r-only.

> 2. Can I expand on the fly a ZFS volume within a file system when the
>     file system it''s attached to a server read-write?
Yes.

-- 
Rich Teer, SCNA, SCSA, SCSECA, OpenSolaris CAB member

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> 1. Can I create  ZFS volumes on a ZFS file system from one server,
>      attach the file system read-write to a different server (to load
data),
>      then detach the file system from that server and attach the file
system
>      read-only to multiple other servers?
I don''t think so today.  There''s no way to read-only import a
pool.
While imported, the server is going to want to be writing metadata, and
the two hosts would clobber each other.

I''ve talked to Symantec engineers about similar read-only imports of
VxVM disk groups (for other reasons).  No one thought there were
insurmountable problems, but they weren''t exactly trivial either.  I
don''t know what ZFS might require for it.
> 2. Can I expand on the fly a ZFS volume within a file system when the
>      file system it''s attached to a server read-write?
You mean like enlarge a LUN while ZFS is using that lun in a pool?  I
think the tricky part is getting the OS to recognize the increased
space.  I''m not sure when ZFS would notice the size increase after that
occurred.

-- 
Darren Dunham                                           ddunham at taos.com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
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