[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Gluster-devel] Server-side AFR + Failover and mixed server/client-s

From: Derek Price
Subject: Re: [Gluster-devel] Server-side AFR + Failover and mixed server/client-side AFR
Date: Tue, 06 May 2008 12:15:23 -0400
User-agent: Thunderbird (Windows/20080421)

Krishna Srinivas wrote:
 >  Is this an issue in server-side-only AFR? I have two servers which are also
 > clients of themselves, and they both list their local subvolume first and
 > remote subvolume second. Is this a problem? What are the possible
 > consequences of this?

 It will be a problem. The "first" subvol is always the "lock" server.
 Consider a case where you are creating a file simultaneously
 on two clients, only one of them should succeed. If AFR's
 subvols order are not same, chances are that both client
 returns success for file creation with same name.

Hence you have "option read-subvlume" to speeden the
read() calls so that it can be done from local subvol.

So, what happens if the "lock" server is the one that goes down? Will that render the whole AFR cluster inoperable, at least for writes?

Why not arrange some sort of voting system for AFR locks, where no specific server, but rather half of the listed servers (maybe the first server listed gets an extra vote in the case of an even number of servers) have to agree to assign the lock (and increment the version # without receiving the data). Then writes could also be done locally and synchronized at leisure.

Derek R. Price
Solutions Architect
Ximbiot, LLC <>
Get CVS and Subversion Support from Ximbiot!

v: +1 248.835.1260
f: +1 248.246.1176

reply via email to

[Prev in Thread] Current Thread [Next in Thread]