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RE: [Xen-API] RE: Questions about the api

To: Julian Chesterfield <Julian.Chesterfield@xxxxxxxxxxxxx>
Subject: RE: [Xen-API] RE: Questions about the api
From: Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>
Date: Thu, 21 Oct 2010 19:10:11 +0100
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Cc: Tomoiaga Cristian <cristi@xxxxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, "xen-api@xxxxxxxxxxxxxxxxxxx" <xen-api@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-API] RE: Questions about the api
> Actually, if Nexenta exposes the underlying ZFS snapshot and clone
> primitives, then you're probably better off just accessing the raw files
> directly over NFS and then using the ZFS snap API for vdi_snapshot and
> vdi_clone. Is there any performance benefit to using iSCSI instead of
> NFS for the data path layer with Nexenta?

It would be interesting to compare the performance of iSCSI vs NFS. In earlier 
versions of Solaris that supported ZFS the iSCSI target wasn't particularly 
performant, so NFS was better than iSCSI, but I imagine they are quite similar 

The main benefits of using iSCSI over NFS are:
 * Easier to do multi-homing
 * metadata (and optionally data) protection with CRCs
 * ability to "fence" other initiators from having access to an image.

That last point is actually a big deal in cloud environments that need HA.


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