[Gluster-devel] AFR bricks - how does it resync question

[DeeDee Park]

Thanks that clears up a lot about what is going on. I am not familiar with 
xattr. I tried getfattr -d <somefile> on both the brick, and glusterfs 
client, and nothing showed up.

Does this information also exist in for directories?

Also, I see the algorithm checks for latest createtime. I think something is 
missing. I would think that  lastmodified time needs to also be kept track 
of to know which brick has the latest version. For Example, if I have Brick1 
and Brick2, and they both exist when a file is created, then B2 goes down. 
Let's say that <somefile> got modified in the interim while B2 was down. 
When B2 comes back up, both files will have the same file create time, but 
B1 will have a newer file modified time. I assume under the current 
algorithm, both files on B1 and B2 would be considered as the same file by 
glusterfs. Oh. my bad, I see now that you are using the trusted.afr.version 
to keep track of which is modified later. I see some of the tradeoffs 
between lastmodified time vs version. Are these times relative to the server 
clock or client clock?

I recall with DFS, that the clock or time management was a huge part of the 
design. I'm using a bunch of test boxes right now (in a production 
environment, this might be less of a problem with well managed boxes), but 
sometimes the boxes are off a little on the clocks as until I remember to 
run NTP. Is there a big impact to glusterfs re-syncing if the clocks are 
off?


>From: "Krishna Srinivas" <krishna at zresearch.com>
>To: "DeeDee Park" <deedee6905 at hotmail.com>
>CC: gluster-devel at nongnu.org
>Subject: Re: [Gluster-devel] AFR bricks - how does it resync question
>Date: Tue, 31 Jul 2007 21:02:05 +0530
>
>DeeDee,
>
>http://lists.gnu.org/archive/html/gluster-devel/2007-07/msg00008.html
>
>See if that helps.
>
>Regards
>Krishna
>
>On 7/31/07, DeeDee Park <deedee6905 at hotmail.com> wrote:
> > If I have two bricks B1, and B2, and they are replicas using AFR.
> > If one of the bricks goes down and has an older copy of a file, and then
> > comes backup,
> > if a file is being appended, how does the AFR know which copy to update?
> >
> > _________________________________________________________________
> > http://newlivehotmail.com
> >
> >
> >
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