[OpenAFS] Re: byte-range lock errors

[Jaap Winius]

Quoting Andrew Deason <adeason@sinenomine.net>:

>> Is it possible to enable support for byte-range locks in this version
>> of OpenAFS,
>
> Well, they are on, sorta. They're on as much as they can be on, with
> current OpenAFS.

I seem to remember a somwhat woozy Matt Benjamin delivering a  
presentation about a solution for this very issue in Pilsen back in  
2010. Will his changes be included in a later version, or are they  
already in this one?

> It doesn't affect you because you're running it on one machine,
> presumably.

It may not affect me as a user, but as a sysadmin I am affected by  
anything abnormal in a log file on a system for which I am  
responsible... Like a splinter in my mind, driving me mad. ;-)

> What it's warning you about is that if you access it from
> multiple machines at the same time, you may encounter some issues.

That's not a danger in this particular case, while on my production  
systems the home directories are no longer in AFS.

On the other hand, if I eventually set up other production  
environments in which the home directories are in AFS, I would prefer  
not to encounter too many issues like this (or worse).

> How often are you seeing these messages? There is some simple
> rate-limiting so you're not supposed to see them for the same process
> more often than once every 2 minutes. But maybe it's that
> once-every-two-minutes that you're talking about :)

It's more often than that. Here's the frequency for a 10-minute period:

01:20:09
01:20:09
01:20:12
01:20:13
01:20:14
01:20:59
01:20:59
01:21:09
01:21:09
01:21:59
01:21:59
01:22:09
01:22:09
01:22:59
01:22:59
01:23:09
01:23:09
01:23:59
01:23:59
01:24:09
01:24:09
01:24:59
01:24:59
01:25:09
01:25:09
01:25:13
01:25:13
01:25:14
01:25:59
01:25:59
01:26:59
01:26:59
01:27:59
01:27:59
01:28:59
01:28:59
01:29:20
01:29:20
01:29:59
01:29:59

That's exactly four times a minute on average. Also, in this case four  
different pids were involved, all related to firefox-bin.

According to lsof, one of the pid numbers involved was associated with  
some 37 locked Firefox/Iceweasel files in my home directory in AFS.  
It's hard to tell for which one(s) the program is trying to request a  
byte-range lock. I could always move part or all of my home directory  
to the local disk (with an SSD, it would undoubtedly be faster that  
way), but that would feel like giving up.

> I think running this should turn them off:
>
> fs messages -show console
> ...

That works, but since I'd have to do this every time I reboot my  
workstation, it's not exactly a very convenient solution.

> But that turns off a lot of other messages, too. There's currently no
> way to turn off the "byte-range locks" messages specifically, though
> doing so of course would not be difficult from a technical perspective.
>
> Do you (or others) know what you'd want such an option to look like? It
> could be yet another thing in /proc/sys/afs...

That would suite me just fine.

Cheers,

Jaap