clarifications on inode64 mount option

clarifications on inode64 mount option

[Ivan.Novick]

Hi all,

My understanding from the documentation is that inode64 allows inode numbers to be 64 bits in size rather than the default of 32.

Is this correct?  Will the option work fine on 32 bit X86 builds?

The documentation also says:
"This is provided for backwards compatibility, but causes problems for backup applications that cannot handle large inode numbers."
Is this a current issue?  Any examples of backup applications that have trouble reading a file system that uses this option?

Cheers,
Ivan Novick

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Re: clarifications on inode64 mount option

[Dave Chinner]

On Sun, Nov 21, 2010 at 07:12:38PM -0500, Ivan.Novick@emc.com wrote:
> Hi all,
> 
> My understanding from the documentation is that inode64 allows
> inode numbers to be 64 bits in size rather than the default of
> 32.
> 
> Is this correct? 

Yes.

> Will the option work fine on 32 bit X86 builds?

Yes, with a few caveats - all userspace applications, libraries, etc
need to use stat64() rather than stat() so that 64 bit inode numbers
can be correctly exported to userspace.

> The documentation also says:
> "This is provided for backwards compatibility, but causes problems
> for backup applications that cannot handle large inode numbers."
> Is this a current issue?  Any examples of backup applications that
> have trouble reading a file system that uses this option?

See this discussion:

http://oss.sgi.com/archives/xfs/2010-04/msg00111.html

EMC Networker is one of the backup programs that has historically
not supported 64 bit inodes. Whether that is still true or not,
maybe you can find out for us. ;)

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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