[Gluster-users] how well will this work

Miles Fidelman mfidelman at meetinghouse.net
Sun Dec 30 18:33:30 UTC 2012

Jeff Darcy wrote:
> On 12/27/12 6:47 PM, Miles Fidelman wrote:
>> John Mark Walker wrote:
>>> In general, I don't recommend any distributed filesystems for VM
>>> images, but I can also see that this is the wave of the future.
>> Ok.  I can see that.
>> Let's say that I take a slightly looser approach to high-availability:
>> - keep the static parts of my installs on local disk
>> - share and replicate dynamic data using gluster
> That, in a nutshell, is the approach that I (and others) often advocate.  Block
> storage should be used sparingly, e.g. for booting and for data served to
> others at a higher level.  I'd say that's true in general, but it's especially
> true for any kind of network block storage.  When network latencies are
> involved, going "up the stack" where operations are expressed at a high
> semantic level will almost always work out better than blocks and locks.

What's the alternative, though?  Ok, for application files (say a word 
processing document) that works, but what about spools, databases, and 
such?  Seems like blocks are the common denominator.
>> - data is triply replicated (allow for 2-node failures)
> Unfortunately, three-way replication is still a bit of a work in progress.
> Some (such as Joe Julian) use it successfully, but they also use it very
> carefully.  I've had to make a few fixes in this area myself recently, and I
> expect to make a few more before I'd say that it's really up to snuff for
> general use.

That's a bit disappointing.   For high-availability applications (like 
mine), 3-way replication would seem to be the major advantage of a 
cluster file system over DRBD.


Miles Fidelman

In theory, there is no difference between theory and practice.
In practice, there is.   .... Yogi Berra

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