openstack team mailing list archive

[Kuo Hugo <tonytkdk@xxxxxxxxx>]

Hi Mark,

Well, the ring without rebalance will not effect anything.
With a update, there're no partitions been assigned to the new
devices.Result of partition numbers of a new device will be 0. Which means
no any object will be calculated for these new devices.

In the case of adding a new server (devices) to the ring, it should still
work properly.
What you need is to understand the mechanism of replicator and the theory
of partions in Swift.

I have to point out a key concept of "partition". It's a "logic partition"
in swift layer instead of a real partition on disk.

When a partition been assigned to a new device. it's much more like that
your parking slot changed from first floor to second floor. Your can won't
be destroyed but wait for moving to new place. :)  Hope it help.

Cheers


+Hugo Kuo+
hugo@xxxxxxxxxxxxxx
tonytkdk@xxxxxxxxx
+886 935004793


2013/6/14 Mark Brown <ntdeveloper2002@xxxxxxxxx>

>
> When a new server is added to an existing cluster, and I now update the
> ring with the new device, but at the same time, I do NOT rebalance, will
> things work correctly?
>
> I am assuming if I don't rebalance, but I do update the ring, the ring has
> the new partition scheme with the new device information, so new data will
> go to the new device. But at the same time, an existing object which
> previously hashed to a specific partition on a specific server can possibly
> hash to a different partition on a different server, so how do old objects
> get accessed? I do understand I should do the rebalance, and I will at a
> certain point in time, but I wanted to understand the behavior if I update
> the ring and don't do the rebalance
>
>
> Cheers,
> -- Mark
>
>
> _______________________________________________
> Mailing list: https://launchpad.net/~openstack
> Post to     : openstack@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~openstack
> More help   : https://help.launchpad.net/ListHelp
>
>