[Gluster-devel] Sharding - Inode write fops - recoverability from failures - design

[Vijay Bellur]

On 02/22/2015 06:08 PM, Krutika Dhananjay wrote:
> Hi,
>
> Please find the design doc for one of the problems in sharding which
> Pranith and I are trying to solve and its solution @
> http://review.gluster.org/#/c/9723/1.
> Reviews and feedback are much appreciated.
>

Can this feature be made optional? I think there are use cases like 
virtual machine image storage, hdfs etc. where the number of metadata 
queries might not be very high. It would be an acceptable tradeoff in 
such cases to not be very efficient for answering metadata queries but 
be very efficient for data operations.

IOW, can we have two possible modes of operation for the sharding 
translator to answer metadata queries?

1. One that behaves like a regular filesystem where we expect a mix of 
data and metadata operations. Your document seems to cover that part 
well. We can look at optimizing behavior for multi-threaded single 
writer use cases after an initial implementation is in place. Techniques 
like eager locking can be applied here.

2. Another mode where we do not expect a lot of metadata queries. In 
this mode, we can visit all nodes where we have shards to answer these 
queries.

-Vijay