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Subject: Re: NFS speed traffic control
From: Shanker Balan <mail@shankerbalan.net>
In-Reply-To: 
 <CA+wMzVK1pZRv5243P0uffbE5VJk6QXCDunE589SFeSiA6qkf6Q@mail.gmail.com>
Date: Mon, 24 Sep 2012 12:45:10 +0530
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To: cloudstack-users@incubator.apache.org

On 24-Sep-2012, at 6:02 AM, Ivan Rodriguez <ivanoch@gmail.com> wrote:

> Dear Cloudstack users,
>=20
> We have several servers provisioning vm's through cloudstack, our =
primary
> storage is coming from a NFS mount point,  we have some high demanding =
and
> important vm's  and some which are not that important but do lots of =
writes
> to the disk, since all the vm's are competing for access to the NFS =
disk,
> one vm can affect the speed of the whole setup, I know cloudstack can
> manage network speed shaping, but I haven't found a way to do network
> storage speed quota or something like that do you guys know if this is
> something that we can do inside cloudstack ?

AWS provides a "Provisioned IOPS" feature for their storage offerings. =
This allows for predictable IO performance to the instances.

=
http://aws.amazon.com/about-aws/whats-new/2012/07/31/announcing-provisione=
d-iops-for-amazon-ebs/

NFS by itself cannot do much to guarantee predictable performance. A =
simple network rate limit can control overall throughput but cannot =
prevent a tenant from performing massive number of small IO operations =
on their virtual disk like what a database would usually do. End of the =
day, NFS does not do multi tenancy very well.

I am guessing that an AWS style "Provisioned IOPS" like "feature" can be =
implemented by having a storage layer that understands multi tenancy and =
natively provides an API to limit/guarantee raw read/write IO operations =
on a per file/object/directory basis. Basically, a storage layer that =
does QoS on a wide range of factors. Cloudstack can then use these =
native APIs to set the desired PIOPS while provisioning instances using =
a plugin connector.

Xenserver seems to allow for I/O priority QoS on the virtual disk. I am =
not sure if this is possible for NFS. The doc seems to suggest that its =
for multiple hosts accessing the same LUN.

=
http://support.citrix.com/servlet/KbServlet/download/28751-102-673823/XenS=
erver-6.0.0-reference.pdf

A workaround would be to have multiple PODs having different QoS =
characteristics - low IO, medium IO, high IO and a very high IO PODs. =
Each POD can use a different primary storage with desired IO =
characteristics or maybe a shared primary storage with QoS features =
enabled.

Am hoping others can share their experiences handling performance =
expectations in a multi tenant cloud using shared storage. Its a very =
interesting problem to solve as clouds in general are notorious for =
their IO performances.

Hth.

-- =20
Shanker Balan
@shankerbalan=