[Linux-cluster] GFS Volume Over NFS

[brem belguebli]

Hi,

NFS is file-oriented, not block device oriented.

On both client and server side, NFS handles filesystems not block devices.

GFS relies on block devices to run, not regular files (like all other
filesystems, except NFS that relies on a lower level filesystem: ext3,
GFS, etc.....)

Indeed, building a GFS on NFS can't easily be done, unless using
emulated block devices thru the loop driver based on regular files
exported via NFS .... but that is more of a trick than a real setup,
without talking of the performance impact.

Brem


2009/9/27 Rafael Micó Miranda <rmicmirregs at gmail.com>:
> Hi Brem,
>
> If Gigi wants to build and storage architecture of "GFS over NFS over
> GFS" i would say "this can't be done".
>
> As i said in my previous mail:
>
> "GFS is a filesystem you use over a device or partition. NFS is a file
> sharing protocol you use to export an already existing filesystem (EXT2,
> EXT3, XFS or GFS itself). When you mount a NFS volume you don't have
> access to a device, so you cant use GFS on it when already mounted."
>
> Which is your opinion in this, Brem?
>
> PS: It's not going bad, thanks for asking
>
> Cheers,
>
> Rafael
>
>
> El dom, 27-09-2009 a las 12:43 +0200, brem belguebli escribió:
>> Hi,
>>
>> The last sentence seems to mean that Gigi wants to create a GFS on top
>> of a NFS FS.
>>
>> This GFS will be then exported thru NFS .
>>
>> Gigi, is that wjat you want to do ?
>>
>> PS: how is it going Rafael ?
>>
>> 2009/9/27 Rafael Micó Miranda <rmicmirregs at gmail.com>:
>> > Hi Gigi,
>> >
>> > El vie, 25-09-2009 a las 19:09 -0500, Mathew, Gigi (JSC-EG)[Jacobs
>> > Technology] escribió:
>> >> Hi:
>> >>
>> >>
>> >>
>> >> I am configuring a Dell EqualLogic iSCSI array in a RHEL 5.3 platform
>> >> with two GFS2 volumes with RedHat Cluster Suite using DRAC (primary)
>> >> and APC (secondary) fencing devices.  In my cluster configuration I
>> >> have DELL Servers (PE R900, PE6800, PE2800, PE1950) Blades (PE M1000,
>> >> PE1955, PE1855).  Now I have few workstations (Precision 7500,
>> >> Precision 5500,  Precision 690) which I would like to share the above
>> >> GFS2 volume over NFS (why?  They are not in the same location and
>> >> currently I use NIS/YPBIND/AUTOFS).  Why should I share it? (Because I
>> >> have user home directories on this GFS2 volume, which has to seen from
>> >> these workstations as they login).  What are the options I have? How
>> >> do I achieve it?  I had seen how to share an NFS over GFS, but NOT the
>> >> other way. Any suggestion will be greatly appreciated.
>> >>
>> >>
>> >>
>> >> Thanks
>> >>
>> >>
>> >>
>> >> Gigi Mathew
>> >>
>> >>
>> >> --
>> >> Linux-cluster mailing list
>> >> Linux-cluster at redhat.com
>> >> https://www.redhat.com/mailman/listinfo/linux-cluster
>> >
>> > Maybe i'm understanding you wrong, let me explain what i have understood
>> > from your explanation:
>> >
>> > 1.- You have several servers sharing iSCSI volumes from an iSCSI array.
>> >
>> > 2.- This servers use GFS2 as filesystem on this volumes to share,
>> > between themselves, the information in them
>> >
>> > 3.- You want to make other computers, workstations, get access to this
>> > info. They are not in the same location/network so they can not access
>> > the iSCSI array by themselves.
>> >
>> > 4.- You plan to share the iSCSI volumes from the array through a NFS
>> > export via the servers which already have access to them, so
>> > workstations will get access to the information via NFS.
>> >
>> > Is this right?
>> >
>> > If so, you should have a look at this document:
>> >
>> > http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Configuration_Example_-_NFS_Over_GFS/index.html
>> >
>> > NFS over GFS2 is, in my opinion, exactly what you need.
>> >
>> > The other option i think you are thinking about, GFS2 over NFS, cant be
>> > done.
>> > GFS is a filesystem you use over a device or partition. NFS is a file
>> > sharing protocol you use to export an already existing filesystem (EXT2,
>> > EXT3, XFS or GFS itself). When you mount a NFS volume you don't have
>> > access to a device, so you cant use GFS on it when already mounted.
>> >
>> > You maybe are thinking in GFS2 over GNDB (global network block device)
>> > or GFS2 over DRBD (distributed redundant block device), but i think
>> > previous suggestion is simpler than this one. You can also have a look
>> > to this approach here:
>> >
>> > http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Global_Network_Block_Device/index.html
>> >
>> > I hope this helps.
>> >
>> > Cheers,
>> >
>> > Rafael
>> >
>> >
>> > --
>> > Rafael Micó Miranda
>> >
>> > --
>> > Linux-cluster mailing list
>> > Linux-cluster at redhat.com
>> > https://www.redhat.com/mailman/listinfo/linux-cluster
>> >
>>
>> --
>> Linux-cluster mailing list
>> Linux-cluster at redhat.com
>> https://www.redhat.com/mailman/listinfo/linux-cluster
> --
> Rafael Micó Miranda
>
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster
>