[gpfsug-discuss] mmchfs -k nfs4 impacts?

Losen, Stephen C (scl) scl at virginia.edu
Mon Aug 29 22:18:15 BST 2022

Hi Jonathan,
Thanks for your reply. I didn't see "-k samba" in the docs. I'll look some more. Also I didn't mention that we also need NFSv4 access and native GPFS, this will not be SMB-only. It will actually be mostly GPFS native. I don't think existing ACLs will be adversely affected. In a test filesystem with "-k all" I set some POSIX ACLs and converted the filesystem to "-k nfs4" and the result looked reasonable.  Plus I ran mmgetacl -k nfs4 on numerous files/dirs with POSIX ACLs in our production filesystem and the results looked promising.

Glad to know that switching the filesystem to -k nfs4 won't be a huge performance hit.
Steve Losen
Research Computing
University of Virginia
scl at virginia.edu  434-924-0640

On 8/29/22, 5:07 PM, "gpfsug-discuss on behalf of Jonathan Buzzard" <gpfsug-discuss-bounces at gpfsug.org on behalf of jonathan.buzzard at strath.ac.uk> wrote:

    On 29/08/2022 18:52, Losen, Stephen C (scl) wrote:

    > Hi,
    > We want to export  SMB shares via Spectrum Scale CES nodes. The 
    > filesystem has ACL style set to “all” and we must set it to nfs4 with 
    > mmchfs -k nfs4 . The filesystem currently has millions of files with 
    > POSIX ACLs. Will this mmchfs command result in any performance impact, 
    > such as a major rewrite of metadata? Thanks.

    The operation will complete very quickly. The bigger risk is that your 
    existing ACL's will go "puff".

    As I understand it GPFS stores each different ACL only once and then it 
    points each file to the ACL. When you change the ACL type they get nuked 
    from recollection but it is a decade now since I played around with 
    that. I stick to NFSv4 ACL's since then because well POSIX ACL's are a 
    bit naff frankly.

    I personally would have thought "-k samba" would have been preferable 
    for your use case mine you ;-)


    Jonathan A. Buzzard                         Tel: +44141-5483420
    HPC System Administrator, ARCHIE-WeSt.
    University of Strathclyde, John Anderson Building, Glasgow. G4 0NG

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