[Discuss] Gluster startup, small-files performance

[ozbek at gmx.com (F. O. Ozbek)]

On 05/14/2014 11:13 AM, Richard Pieri wrote:
> F. O. Ozbek wrote:
>> The data gets written. We have tested it.
>
> Ignoring fsync/O_SYNC means that the file system driver doesn't flush
> its write buffers when instructed to do so. Maybe the data gets written.
> Maybe not. You can't be sure of it unless writes are atomic, and you
> don't get that from MooseFS.
>
> So, like I said, good luck with that. Because outages like the one that
> clobbered Cambridge back in November 2012 happen.
>

That is the whole point, "doesn't flush its write buffers when 
instructed to do so". You don't need to instruct. The data gets written
all the time. When we have done the tests, we have done tens of 
thousands of writes (basically checksum'ed test files) and
read tests succeeded all the time. OK, I admit, you probably
do not want to run your transactional financial applications on moosefs
but the reality is that these filesystems are used in research
environments where high I/O bandwidth is the key.
The fact that it doesn't support forcing the buffer to the disk
is not the problem in this case. Glusterfs will start giving
you random I/O errors under heavy load. How is that any good?

I don't know what you are referring to in Cambridge but
we are not Cambridge.

Fevzi