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From "Rob C." <iose...@gmail.com>
Subject Re: Secondary Storage IP Subnet: Is it Optional or Mandatory?
Date Fri, 18 Oct 2013 17:18:42 GMT
Hi,

Thanks Sanjeev and Geoff for your replies.  I have a few follow-up
questions.

A. The document I referenced states "if a physical storage interface was not
specified when creating the zone this interface will not exist" in
reference to eth3 (the SSVM storage network interface).  Is that no longer
the case?  I don't see the logic of having a second virtual NIC on the same
subnet.

B. I know that having multiple NICs on the same system connected to the
same subnet can sometimes cause network issues.  If this is to be the
resulting configuration on the SSVM, is there anything I should watch out
for?  What has been done to head off any issues that could result from this
configuration?

C. Aside from performance/redundancy concerns, can you offer any general
comments regarding the wisdom of opting not to have a secondary storage IP
subnet?  Beyond being technically possible and permitted, is this a common
and accepted approach?


For my better understanding, and because I am weighing the options, I'd
still appreciate answers to my questions about the Secondary Storage
network, re-posted below:

4. I haven't found any documentation that helps with planning the size of
the Secondary Storage network -- besides the NFS server and the SSVM, what
other devices must have an IP address on this network?

5. How are IP addresses for devices on the Secondary Storage network
assigned?  In the case of the SSVM it must be dynamic, but if I were to
manually put a CloudStack host onto this network (for convenience), what
assures that the same IP address won't also get handed out to an SSVM?

6. Is it permitted to place the Secondary Storage traffic onto its own
dedicated vSwitch on ESXi?  According to the Installation Guide under
section 8.3.5.1.1 Separating Traffic: "*CloudStack allows you to use
vCenter to configure three separate networks per ESXi host. *...*  The
allowed networks for configuration are public, guest, and private (for
management and usually storage traffic).*"  This would suggest that storage
traffic must share the same vSwitch as management traffic.

Thanks again,
Rob



From: Geoff Higginbottom <geoff.higginbottom@shapeblue.com>
> Date: Thu, Oct 17, 2013 at 2:56 AM
> Subject: Re: Secondary Storage IP Subnet: Is it Optional or Mandatory?
> To: "<users@cloudstack.apache.org>" <users@cloudstack.apache.org>
>
>
> Hi Rob,
>
> The 'storage' network is indeed optional so your plan to not use it is
> perfectly valid.
>
> Simply put the NFS server on the management network or ensure there is a
> route to it via the management network.
>
> The SSVM will still get a virtual interface dedicated to storage, but it
> will be assigned an additional IP address from the management ip range.
>
> There is no need to configure any ip range for storage, and if using the
> add zone wizard it will not prompt you for one.
>
> Regards
>
> Geoff Higginbottom
> CTO / Cloud Architect
>
>
> D: +44 20 3603 0542<tel:+442036030542> | S: +44 20 3603 0540<tel:
> +442036030540> | M: +447968161581<tel:+447968161581>
>
> geoff.higginbottom@shapeblue.com<mailto:geoff.higginbottom@shapeblue.com>
> | www.shapeblue.com
>
> ShapeBlue Ltd, 53 Chandos Place, Covent Garden, London, WC2N 4HS
>
>
>
> On 17 Oct 2013, at 01:08, "Rob C." <ioserve@gmail.com<mailto:
> ioserve@gmail.com>> wrote:
>
> Hi,
>
> According to some (possibly old) documentation I read, I have the
> impression that it is *optional* to define a secondary storage IP subnet.
>
>
> Note, my questions are all in the context of:
> - CloudStack 4.2
> - ESXi hosts / vSphere 5.1
> - Primary Storage is VMFS via fiber channel
> - Advanced Networking
>
> Here is the document to which I am referring, along with the relevant
> quotes:
> CloudStack System VMs:
>
> https://cwiki.apache.org/confluence/download/attachments/30149076/Cloudstack+System+VMs.pdf
> *"Network Terminology -> Storage: As it relates to CloudStack, this is an
>
> optional network dedicated to secondary storage. If not specified, the
> management network will be assumed for this role."*
>
> *"SSVM -> eth3 (storage): Note if a physical storage interface was not
> specified when creating the zone this interface will not exist. Storage
> traffic will assume the management interface"*
>
>
> My Questions:
> 1. Is the above-referenced document accurate for CloudStack 4.2?
>
> 2. Do I interpret correctly that I don't need to define an IP subnet for
> Secondary Storage?
>
> 3. I have noticed that the CloudStack 4.2 Installation Guide, section 2.8.3
> "Advanced Zone Network Traffic Types", for the type "Storage" says: *"You
> must configure the IP range to use for the storage network."*
>
>
> http://cloudstack.apache.org/docs/en-US/Apache_CloudStack/4.2.0/html-single/Installation_Guide/index.html#advanced-zone-network-traffic-types
> How am I to interpret the quoted statement?  Is it saying that I must
> configure a range regardless, or only if I *opt* to have a Secondary
>
> Storage network?  If there is no Secondary Storage IP subnet, would I enter
> a range selected from the Management IP subnet?
>
> I am aware of the redundancy and performance benefits to using separate
> interfaces, this is not my concern here.  My idea is to have a simplified
> CloudStack architecture by using a single IP subnet for CloudStack
> Management, and putting the NFS server on the same subnet (NFS to be used
> for Secondary Storage only).
>
> If your response is that a defined Secondary Storage IP subnet is a
> mandatory requirement, then I have a few other questions regarding this
> network:
> 4. I haven't found any documentation that helps with planning the size of
> the Secondary Storage network -- besides the NFS server and the SSVM, what
> other devices must have an IP address on this network?
>
> 5. How are IP addresses for devices on the Secondary Storage network
> assigned?  In the case of the SSVM it must be dynamic, but if I were to
> manually put a CloudStack host onto this network (for convenience), what
> assures that the same IP address won't also get handed out to an SSVM?
>
> 6. Is it permitted to place the Secondary Storage traffic onto its own
> dedicated vSwitch on ESXi?  According to the Installation Guide under
> section 8.3.5.1.1 Separating Traffic: "*CloudStack allows you to use
> vCenter to configure three separate networks per ESXi host. *...*  The
>
> allowed networks for configuration are public, guest, and private (for
> management and usually storage traffic).*"  This would suggest that storage
>
> traffic must share the same vSwitch as management traffic.
>
> If I am missing something fundamental, and/or asking the wrong questions,
> please correct me!  Same goes if you have some general insight into the
> pros and cons of having a Secondary Storage IP subnet.
>
> Many thanks!
> Rob
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