pNFS Access Permissions Check - - PowerPoint PPT Presentation

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pNFS Access Permissions Check draft-faibish-nfsv4-pnfs-access-permissions-check-03.txt IETF 78 NFSv4 WG Meeting, July 28, 2010 Sorin Faibish sfaibish@emc.com David Black - EMC Mike Eisler - NetApp Jason Glasgow - Google Problem Statement

SLIDE 1

pNFS Access Permissions Check

draft-faibish-nfsv4-pnfs-access-permissions-check-03.txt

IETF 78 NFSv4 WG Meeting, July 28, 2010

Sorin Faibish sfaibish@emc.com David Black - EMC Mike Eisler - NetApp Jason Glasgow - Google

SLIDE 2

IETF78 NFSv4 WG, 07/28/2010 2

Problem Statement

 pNFS clients receives valid layout to

a DS but cannot access data server

 MDS has no information about why

client is doing all I/O through server

 This is a serious scalability problem

for pNFS defeating it’s purpose pNFS protocol Control protocol Storage-access protocol

Metadata Server Data Servers Client

X X

SLIDE 3

IETF78 NFSv4 WG, 07/28/2010 3

Changes from -02 version

 Use additional layout return types

 Drop approach of extending layout-type-specific layout return

data

 Extend use of layout return types to cover any loss of

client to data server connectivity

 Not just access permission issues  Example: Partial network outage

 Single op can report multiple inaccessible data servers  Drop the callback

 Removes server ability to ask clients to check device access

SLIDE 4

IETF78 NFSv4 WG, 07/28/2010 4

To Do list

 Client guidance on when to report

problems



Client should try a few times before report



Report will be treated as serious/persistent

 NFS4ERR_PERM was misused and will

be replaced with NFS4ERR_ACCESS

 List NFS errors that can be used  REQUEST: Accept as WG draft

SLIDE 5

IETF78 NFSv4 WG, 07/28/2010 5

Questions for discussion

 Label allowed NFS errors as

MANDATORY vs. OPTIONAL?



Purpose of doing this?

 Dealing with problem resolution



How does MDS or client find out?



No protocol mechanisms to detect restored data server access in -03

 Extend to report SCSI errors?



Recommendation: No.

SLIDE 6

IETF78 NFSv4 WG, 07/28/2010 6

Acknoledgements

Thanks to:

David Black for help with the cleanup of language and nits Jason Glasgow for the implementation details Tom Haynes, Craig Everhart, Benny Halevy and Brian Wong for all the very constructive comments and recommendations