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Re: Swift questions.


Thanks for the response David.

I do understand Swift, by its design, tries to keep things in balance among various nodes. I was curious what it does when it encounters a full partition(say hard disk is full)? Lets just say it is balanced and the all nodes are nearing capacity. If I dont add any nodes, what happens when it tries to write on a specific node (which it was directed to based on the hashing ring) and there is not enough space to write the object?

Also, what does it use to determine a full partition? Does it use a df? 


 From: David Hadas <DAVIDH@xxxxxxxxxx>
To: Mark Brown <ntdeveloper2002@xxxxxxxxx> 
Cc: "openstack@xxxxxxxxxxxxxxxxxxx" <openstack@xxxxxxxxxxxxxxxxxxx> 
Sent: Sunday, May 12, 2013 10:36 PM
Subject: Re: [Openstack] Swift questions.


Regarding your first Q:

Swift evenly balance the hard-drives such that in a correctly configured system, you should expect one hard-drive being more full than the other. 
There is manual a mechanism in swift to balance hard-drives by moving partitions to/from hard-drive but you should need to use it under normal conditions, it is likely that if your had-drives get full the right thing to do would be to add more hard-drives.

In any case you should care not about individual partitions 'getting full' as partitions are not allocated any specific space and can grow and shrink as needed as long as the hard-drive they are in have space.


David Hadas
Research Staff Member, Master Inventor

IBM Research Labs, Haifa
Tel:    Int+972-4-829-6104
Fax:   Int+972-4-829-6112

-----"Openstack" <openstack-bounces+davidh=il.ibm.com@xxxxxxxxxxxxxxxxxxx> wrote: -----
To: "openstack@xxxxxxxxxxxxxxxxxxx" <openstack@xxxxxxxxxxxxxxxxxxx>
From: Mark Brown 
Sent by: "Openstack" 
Date: 05/12/2013 07:50PM
Subject: [Openstack] Swift questions.

Hello guys,
Been looking at Swift for some projects, and had some very basic questions.

1. How does Swift determine a certain partition is full? And when it does detect that, what does it do? Does it return an error to the client?

2. Regarding container sync, has anyone used container sync in their implementations? It would be great to know your experiences, because real world use case studies are scarce:)

-- Mark

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