[gpfsug-discuss] Unix mode bits and mmapplypolicy

[Bryan Banister]

Before I try these mmfsctl commands, what are the implications of suspending writes?  I assume the entire file system will be quiesced?  What if NSD clients are non responsive to this operation?  Does a deadlock occur or is there a risk of a deadlock?

Thanks in advance!
-Bryan

From: gpfsug-discuss-bounces at gpfsug.org [mailto:gpfsug-discuss-bounces at gpfsug.org] On Behalf Of makaplan at us.ibm.com
Sent: Friday, August 28, 2015 11:55 AM
To: gpfsug-discuss at gpfsug.org
Cc: gpfsug-discuss at gpfsug.org
Subject: Re: [gpfsug-discuss] Unix mode bits and mmapplypolicy

This is due to a design trade-off in mmapplypolicy.
Mmapplypolicy bypasses locks and caches - so it doesn't "see" inode&metadata changes until they are flushed to disk.
I believe this is hinted at in our publications.

You can force a flush with`mmfsctl fsname suspend-write; mmfsctl fsname resume`


----- Original message -----
From: aquan <aquan at o2.pl<mailto:aquan at o2.pl>>
Sent by: gpfsug-discuss-bounces at gpfsug.org<mailto:gpfsug-discuss-bounces at gpfsug.org>
To: gpfsug-discuss at gpfsug.org<mailto:gpfsug-discuss at gpfsug.org>
Cc:
Subject: [gpfsug-discuss] Unix mode bits and mmapplypolicy
Date: Fri, Aug 28, 2015 11:12 AM

Hello,

This is my first time here. I'm a computer science student from Poland
and I use GPFS during my internship at DESY. GPFS is a completely new
experience to me, I don't know much about file systems and especially those
used on clusters.
I would like to ask about the unix mode bits and mmapplypolicy.
What I noticed is that when I do the following:

1. Recursively call chmod on some directory (i.e. chmod -R 0777 some_directory)
2. Call mmapplypolicy to list mode (permissions),

the listed modes of files don't correspond exactly to the modes that I set with chmod.
However, if I wait a bit between step 1 and 2, the listed modes are correct.
It seems that the mode bits are updated somewhat asynchronically and if I run
mmapplypolicy too soon, they will contain old values.

I would like to ask if it is possible to make sure that before calling mmputacl,
the mode bits of that directory will be up to date on the list generated by a policy?

- Omer Sakarya
_______________________________________________
gpfsug-discuss mailing list
gpfsug-discuss at gpfsug.org
http://gpfsug.org/mailman/listinfo/gpfsug-discuss


________________________________

Note: This email is for the confidential use of the named addressee(s) only and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you are hereby notified that any review, dissemination or copying of this email is strictly prohibited, and to please notify the sender immediately and destroy this email and any attachments. Email transmission cannot be guaranteed to be secure or error-free. The Company, therefore, does not make any guarantees as to the completeness or accuracy of this email or any attachments. This email is for informational purposes only and does not constitute a recommendation, offer, request or solicitation of any kind to buy, sell, subscribe, redeem or perform any type of transaction of a financial product.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gpfsug.org/pipermail/gpfsug-discuss_gpfsug.org/attachments/20150829/150ec7fc/attachment-0002.htm>