I would agree, except that Alex indicated that noatime causes the correct behavior.
On Wed, Dec 4, 2013 at 11:24 PM, Brian O'Neill <[email protected]> wrote: > I'm thinking the atime is being updated by the server because the server > accessed the file in order to serve it... > > Alex Aminoff <[email protected]> wrote: >> >> On 12/4/2013 10:21 PM, Matt Simmons wrote: >> >>> My knowledge is somewhat limited to the Linux world, but in my >>> experience I've never seen a mount be set to 'ro' and have anything >>> updated. I hate to use the term 'flabbergasted', but I'm pretty sure >>> that if I saw an implementation that didn't respect the 'ro' flag, I'd >>> be at the very least 'put out', and perhaps even vitriolic. >> >> >> Yeah, flabbergasted is a good description of how I felt. >> >> Nevertheless, I tested it and unless I messed up my test, an NFS mount >> with -o ro, you read a file on the mounted FS, and the access time is >> updated. >> >> For the test the server was a NetApp, the client was Linux. >> >> There is a mount flag -o noatime that does what I want. But I would >> argue that this is not right. The simplest be >> havior >> - nothing is ever >> written period - should be what you get by default, and then there could >> be a flag that enables exceptional behavior, that is updating the access >> time. >> >> I can squint and see why it would be the way it is. One perspective is >> that the naive assumption is that reading off a RO filesystem should be >> just like reading any other way; when you read, the OS conveniently >> remembers when you did. The inconsistency of "writing" to a read-only >> thing is less important than the inconsistency of not updating the >> access time when the file is read. >> >> But what if the underlying device is not capable of recording access >> times, like a CD-ROM? Can you look at the mount options and see that a >> CDROM is read-only? But then you can't know whether access times will be >> updated unless you use some other method to find out what the underlying >> device is. So that's an abstraction violation. Bother, I >> don't >> have a >> unix box easily to hand where I can check what the mount options on a >> CDROM look like. >> >> I'm not sure if this is just grousing, or flame bait, or a gotcha that >> every sysadmin should know because there is no way to anticipate it. >> >> - Alex >> >> --Matt >>> >>> >>> >>> On Tue, Dec 3, 2013 at 2:21 PM, Alex Aminoff <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> >>> Hi folks. I encountered something odd. >>> >>> Suppose you mount a file system read only. You read a file from >>> it. Does >>> the access time of that file get updated? >>> >>> In one place I found documentation saying no. But other places seem to >>> imply that it does. >>> >>> Does the answer change if it is an NFS mount? >>> >>> I have deliberately left details of what OS I'm using out, becau >>> se >>> it >>> seems to me that the answer should be consistent, and if it is not, it >>> should be documented publicly. >>> >>> - Alex Aminoff >>> BaseSpace.net, NBER >>> >>> >>> >>> >>> ------------------------------ >>> >>> bblisa mailing list >>> [email protected] <mailto:[email protected]> >>> http://www.bblisa.org/mailman/listinfo/bblisa >>> >>> >>> >>> >>> -- >>> "Today, vegetables... Tomorrow, the world!" >>> >>> >>> ------------------------------ >>> >>> bblisa mailing list >>> [email protected] >>> http://www.bblisa.org/mailman/listinfo/bblisa >>> >> >> ------------------------------ >> >> bblisa mailing list >> [email protected] >> http://www.bblisa.org/mailman/listinfo/bblisa >> >> > -- > Sent from my Android phone with K-9 Mail. Please excuse my brevity. > > _______________________________________________ > bblisa mailing list > [email protected] > http://www.bblisa.org/mailman/listinfo/bblisa > -- "Today, vegetables... Tomorrow, the world!"
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