[Gluster-users] GlusterFS compared to KosmosFS (now called cloudstore)?
gowda at zresearch.com
Tue Oct 21 03:09:18 UTC 2008
On Tue, Oct 21, 2008 at 1:40 AM, Keith Freedman <freedman at freeformit.com>wrote:
> At 12:12 PM 10/20/2008, Stas Oskin wrote:
> >Thanks for all the answers.
> >I should say that indeed especially the metaserver-less (P2P?)
> >approach of GlusterFS makes it a very attractive option, as it
> >basically cancels any single points of failure.
> I think it's important that people understand the tradeoffs.
> Having a central metaserver insures the integrity of the data.
> With Gluster, by not having a meta server, they introduce different
> problems (and different solutions).
> With AFR, you can get into a split brain situation. So examining
> glusters split brain resolution would be necessary and you'd have to
> determine if you're comfortable with the tradeoffs. In my view, it's
> a good workable solution but it may not work for everyone.
> The other issue is the namespace brick on the unify translator. this
> is effectively a meta-data like thing. you can afr the namespace
> brick to provide additional availability, but if your namespace brick
> is unavailable then you have a similar problem as you have with a
> metadata server outage in another solution.
new DHT translator scheduled for 1.4.0 release provides similar
functionality as unify (file scheduling) and does not use a namespace brick.
thus DHT completely avoids meta-data server concept from glusterfs.
> So, while I personally think gluster is one of the "best" solutions
> out there, it's because the numbers for my situation point in that
> direction but it wont for everyone.
> >My largest concert over GlusterFs is really the luck of central
> >administration tool. Modifying the configuration files on every
> >server/client with every topology change becomes a hurdle on 10
> >servers already, and probably impossbile beyond 100.
> in most cases, your client configurations are pretty much identical,
> so maintaining these is relatively simple. If your server topology
> changes often then it can be inconvenient, partly because you have to
> deal with IP addresses.
> It's also not good for certain grid operating systems which use
> internal IP's and the IP's change randomly, or if you for some reason
> have servers using dhcp.
> >Hence, I'm happy to hear version 1.4 will have some kind of a web
> >interface. The only questions are:
> >1) Will it support a central management of all serves/clients,
> >including the global AFR settings?
> >2) When it comes out? :)
> >2008/10/20 Vikas Gorur <<mailto:vikasgp at gmail.com>vikasgp at gmail.com>
> >2008/10/18 Stas Oskin <<mailto:stas.oskin at gmail.com>stas.oskin at gmail.com
> > > Hi.
> > >
> > > I'm evaluating GlusterFS for our DFS implementation, and wondered how
> > > compares to KFS/CloudStore?
> > >
> > > These features here look especially nice
> > >
> > (<http://kosmosfs.sourceforge.net/features.html>
> > Any idea what of them exist
> > > in GlusterFS as well?
> >Here's how GlusterFS compares to KFS, feature by feature:
> > > Incremental scalability:
> >Currently adding new storage nodes requires a change in the config
> >file and restarting servers and clients. However, there is no need to
> >move/copy data or perform any other maintenance steps. "Hot add"
> >capability is planned for the 1.5 release.
> > > Availability
> >GlusterFS supports n-way data replication through the AFR translator.
> > > Per file degree of replication
> >GlusterFS used to have this feature, but it was dropped due to lack
> >of interest. It would not be too hard to bring it back.
> > > Re-balancing
> >The DHT and unify translators have extensive support for distributing
> >data across nodes. One can use unify schedulers to define file creation
> >policies such as:
> >* ALU - Adaptively (based on disk space utilization, disk speed, etc.)
> >schedule file creation.
> >* Round robin
> >* Non uniform (NUFA) - prefer a local volume for file creation and use
> >ones only when there is no space on the local volume.
> > > Data integrity
> >GlusterFS arguably provides better data integrity since it runs over
> >an existing filesystem, and does not access disks at the block level.
> >Thus in the worst case (which shouldn't happen), even if GlusterFS
> >crashes, your data will still be readable with normal tools.
> > > Rack-aware data placement
> >None of our users have mentioned this need until now, thus GlusterFS
> >has no rack awareness. One could incorporate this intelligence into
> >our cluster translators (unify, afr, stripe) quite easily.
> > > File writes and caching
> >GlusterFS provides a POSIX-compliant filesystem interface. GlusterFS
> >has fine-tunable caching translators, such as read-ahead (to read ahead),
> >write-behind (to reduce write latency), and io-cache (caching file data).
> > > Language support
> >This is irrelevant to GlusterFS since it is mounted and accessed as a
> >filesystem, through FUSE. This means all your applications can run
> >on GlusterFS
> >without any modifications.
> > > Deploy scripts
> >Users have found GlusterFS to be so simple to setup compared to other
> >cluster filesystems that there isn't really a need for deploy scripts. ;)
> > > Local read optimization
> >As mentioned earlier, if your data access patterns justify it (that
> >is, if users generally access local data and only occassionly want
> >remote data), you can configure 'unify' with the NUFA scheduler to achieve
> >In addition, I'd like to mention two particular strengths of GlusterFS.
> >1) GlusterFS has no notion of a 'meta-server'. I have not looked through
> >KFS' design in detail, but the mention of a 'meta-server' leads me to
> >believe that failure of the meta-server will take the entire cluster
> >Please correct me if the impression is wrong.
> >GlusterFS on the other hand has no single point of failure such as central
> >meta server.
> >2) GlusterFS 1.4 will have a web-based interface which will allow
> >you to start/stop GlusterFS, monitor logs and performance, and do
> >other admin activities.
> >Please contact us if you need further clarifications or details.
> >Vikas Gorur
> >Engineer - Z Research
> >Gluster-users mailing list
> >Gluster-users at gluster.org
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> Gluster-users at gluster.org
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