NFS for "RAW" file system

[M.sureshkumar]

Hi All,

I want to export raw file system i.e via "NFS".How to export "raw" file system in hp-unix.we have 20 gb raw file system in one system and we can use this raw file system to another system i.e via NFS.

If it is possible, pls give the procedure.

Regards,
Sureshkumar.

[Leif Halvarsson_2]

Hi,

No, NFS only allow exporting filesystem, not raw devices.

The concept for "exporting" raw devices (disks,LUN, tape etc.) is SAN.

[Bill Hassell]

Not possible. There is no such thing as a raw filesystem. What you have are raw disks (lvols) which contain application-specific data. There are no files on these raw volumes at all. Your application (such as Informix or Sybase) has starting/ending block numbers for things like indexes and datastores but no files and no directories.

NFS means Networked File System and requires real files and directories on the local (server) system so the client can see these files. NFS has no concept of raw blocks of data.

[Mohanasundaram_1]

Hi Suresh,

May I ask you why you want to export a "raw" partition?

Are you having Oracle RAC? If the purpose is for some backup, it involves some different configurations.

Raw partition cannot be NFS exported as NFS is only meant to export filesystems over the network, not raw partitions.

If you let us know what you want to achieve, then many people may give you better suggestions.

With regards,
Mohan.

[M.sureshkumar]

Hi

We have created oracle partions on one system.Now I want to copy those raw file system to another system.So we need nfs for this one.

Thanks,
Suresh.

[Mohanasundaram_1]

Hi Suresh,

Read carefully what Bill Hassell has written above this.

There is nothing called "raw" file system.

If you want to copy data from here to another server, then you may perform a DD on that LVOL and restore it on the other system.

Though I am not sure if your purpose will be served by doing this. The other method is export the data, import to the other server.

DD can be done as follows:
source:
dd if=/dev/vg02/lol3 of=/dev/rmt/0m bs=1024k

destination:

dd if=/dev/rmt/0m of=/dev/vg03/lvol5 bs=1024k

Remember, you may end up using more tapes, as each lvol has to be copied in a seperate tape. There is no such thing as appending.

Alternately, you can use backup softwares which can take raw backups and restore.

With regards,
Mohan.

[Leif Halvarsson_2]

Hi,
Do you want to clone the Oracle database to a different system ?

NFS is not an option for copying raw devices, it only apply to filesystem.

As mentioned by other, dd is an alternative, a better (easier) is Data Protector.

Another alternative is to clone the database, using Oracle RMAN.

[C. Beerse]

This gives me the next ideas:

From a unix point of view, you might be able to export the directory in which you have the devices. Then, on the target mount this directory and see if you can use these device-files. On the target, you need to access these devices as files kind of like you can mount a iso-image.

From a storage point of view, I see this as a kind of iscsi export. On the source machine, get some iscsi-emulating software and "iscsi-export" the device. On the target-machine just use this device with iscsi-drivers.

If it is just to dump data from one disk to an other (or from one machine to an other) best to hook the target disk to the source machine and use `dd` to dump the data. Then put the target disk in its target machine and off you go.

[Bill Hassell]

Just to clarify, device files only have meaning on the local system. A device file is really just two numbers: major (the driver ID) and minor (options for the driver). NFS can indeed export /dev but the remote system won't be able to use these device files as they have no meaning.