[Discuss] Gluster startup, small-files performance

[richard.pieri at gmail.com (Richard Pieri)]

F. O. Ozbek wrote:
> If you lose power to your entire storage cluster, you will lose
> some data, this is true on almost all filesystems.(including moosefs and
> glusterfs)

If writes are atomic -- that is, the file system driver and underlying
hardware honor fsync calls -- then you won't lose anything that's been
completed because all completed writes have been committed to
non-volatile storage. You will lose incomplete writes but the clients
will know it (fsync calls time out or return errors) and can retry or
invoke error handlers.


> It is possible to setup a moosefs cluster with redundant metadata
> servers in separate locations (and chunk servers in separate locations.)

A catastrophic failure at the wrong time (is there ever a right time?)
will leave you with lost or corrupted data no matter how many parallel
storage clusters you have.


> This will save you from power outages as long as you don't lose power
> in all the locations at the same time. Keep in mind these servers
> are in racks with UPS units and generator backups.

So are Amazon's EC2 racks. Yet:
http://www.zdnet.com/amazon-web-services-suffers-outage-takes-down-vine-instagram-flipboard-with-it-7000019842/
http://venturebeat.com/2012/10/23/amazon-ec2-outage-restored/
http://money.cnn.com/2011/04/21/technology/amazon_server_outage/

-- 
Rich P.