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From Simon Weller <swel...@ena.com>
Subject RE: storage affinity groups
Date Fri, 09 Sep 2016 23:05:38 GMT
Why not just use different primary storage per cluster. You then can control your storage failure
domains on a cluster basis.

Simon Weller/ENA
(615) 312-6068

-----Original Message-----
From: Will Stevens [wstevens@cloudops.com]
Received: Friday, 09 Sep 2016, 5:46PM
To: dev@cloudstack.apache.org [dev@cloudstack.apache.org]
Subject: Re: storage affinity groups

I have not really thought through this use case, but off the top of my
head, you MAY be able to do something like use host anti-affinity and then
use different primary storage per host affinity.  I know this is not the
ideal solution, but it will limit the primary storage failure domain to a
set of affinity hosts.  This pushes the responsibility of HA to the
application deployer, which I think you are expecting to the be case
anyway.  You still have a single point of failure with the load balancers
unless you implement GSLB.

This will likely complicate your capacity management, but it may be a short
term solution for your problem until a better solution is developed.

If I think of other potential solutions I will post them, but that is what
I have for right now.

*Will STEVENS*
Lead Developer

*CloudOps* *| *Cloud Solutions Experts
420 rue Guy *|* Montreal *|* Quebec *|* H3J 1S6
w cloudops.com *|* tw @CloudOps_

On Fri, Sep 9, 2016 at 3:44 PM, Yiping Zhang <yzhang@marketo.com> wrote:

> Will described my use case perfectly.
>
> Ideally, the underlying storage technology used for the cloud should
> provide the reliability required.  But not every company has the money for
> the best storage technology on the market. So the next best thing is to
> provide some fault tolerance redundancy through the app and at the same
> time make it easy to use for end users and administrators alike.
>
> Regards,
>
> Yiping
>
> On 9/9/16, 11:49 AM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com> wrote:
>
>     Yep, based on the recent e-mail Yiping sent, I would agree, Will.
>
>     At the time being, you have two options: 1) storage tagging 2)
> fault-tolerant primary storage like a SAN.
>     ________________________________________
>     From: williamstevens@gmail.com <williamstevens@gmail.com> on behalf
> of Will Stevens <wstevens@cloudops.com>
>     Sent: Friday, September 9, 2016 12:44 PM
>     To: dev@cloudstack.apache.org
>     Subject: Re: storage affinity groups
>
>     My understanding is that he wants to do anti-affinity across primary
>     storage endpoints.  So if he has two web servers, it would ensure that
> one
>     of his web servers is on Primary1 and the other is on Primary2.  This
> means
>     that if he loses a primary storage for some reason, he only loses one
> of
>     his load balanced web servers.
>
>     Does that sound about right?
>
>     *Will STEVENS*
>     Lead Developer
>
>     *CloudOps* *| *Cloud Solutions Experts
>     420 rue Guy *|* Montreal *|* Quebec *|* H3J 1S6
>     w cloudops.com *|* tw @CloudOps_
>
>     On Fri, Sep 9, 2016 at 2:40 PM, Tutkowski, Mike <
> Mike.Tutkowski@netapp.com>
>     wrote:
>
>     > Hi Yiping,
>     >
>     > Reading your most recent e-mail, it seems like you are looking for a
>     > feature that does more than simply makes sure virtual disks are
> roughly
>     > allocated equally across the primary storages of a given cluster.
>     >
>     > At first, that is what I imagined your request to be.
>     >
>     > From this e-mail, though, it looks like this is something you'd like
> users
>     > to be able to personally choose (ex. a user might want virtual disk
> 1 on
>     > different storage than virtual disk 2).
>     >
>     > Is that a fair representation of your request?
>     >
>     > If so, I believe storage tagging (as was mentioned by Marty) is the
> only
>     > way to do that at present. It does, as you indicated, lead to a
>     > proliferation of offerings, however.
>     >
>     > As for how I personally solve this issue: I do not run a cloud. I
> work for
>     > a storage vendor. In our situation, the clustered SAN that we
> develop is
>     > highly fault tolerant. If the SAN is offline, then it probably means
> your
>     > entire datacenter is offline (ex. power loss of some sort).
>     >
>     > Talk to you later,
>     > Mike
>     > ________________________________________
>     > From: Yiping Zhang <yzhang@marketo.com>
>     > Sent: Friday, September 9, 2016 11:08 AM
>     > To: dev@cloudstack.apache.org
>     > Subject: Re: storage affinity groups
>     >
>     > I am not a Java developer, so I am at a total loss on Mike’s
> approach. How
>     > would end users choose this new storage pool allocator from UI when
>     > provisioning new instance?
>     >
>     > My hope is that if the feature is added to ACS, end users can assign
> an
>     > anti-storage affinity group to VM instances, just as assign anti-host
>     > affinity groups from UI or API, either at VM creation time, or update
>     > assignments for existing instances (along with any necessary VM
> stop/start,
>     > storage migration actions, etc).
>     >
>     > Obviously, this feature is useful only when there are more than one
>     > primary storage devices available for the same cluster or zone (in
> case for
>     > zone wide primary storage volumes).
>     >
>     > Just curious, how many primary storage volumes are available for your
>     > clusters/zones?
>     >
>     > Regards,
>     > Yiping
>     >
>     > On 9/8/16, 6:04 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> wrote:
>     >
>     >     Personally, I think the most flexible way is if you have a
> developer
>     > write a storage-pool allocator to customize the placement of virtual
> disks
>     > as you see fit.
>     >
>     >     You extend the StoragePoolAllocator class, write your logic, and
>     > update a config file so that Spring is aware of the new allocator and
>     > creates an instance of it when the management server is started up.
>     >
>     >     You might even want to extend ClusterScopeStoragePoolAllocator
>     > (instead of directly implementing StoragePoolAllocator) as it
> possibly
>     > provides some useful functionality for you already.
>     >     ________________________________________
>     >     From: Marty Godsey <marty@gonsource.com>
>     >     Sent: Thursday, September 8, 2016 6:27 PM
>     >     To: dev@cloudstack.apache.org
>     >     Subject: RE: storage affinity groups
>     >
>     >     So what would be the best way to do it? I use templates to make
> it
>     > simple for my users so that the Xen tools are already installed as an
>     > example.
>     >
>     >     Regards,
>     >     Marty Godsey
>     >
>     >     -----Original Message-----
>     >     From: Yiping Zhang [mailto:yzhang@marketo.com]
>     >     Sent: Thursday, September 8, 2016 7:55 PM
>     >     To: dev@cloudstack.apache.org
>     >     Subject: Re: storage affinity groups
>     >
>     >     Well, using tags leads to proliferation of templates or service
>     > offerings etc. It is not very scalable and gets out of hand very
> quickly.
>     >
>     >     Yiping
>     >
>     >     On 9/8/16, 4:25 PM, "Marty Godsey" <marty@gonsource.com> wrote:
>     >
>     >         I do this by using storage tags. As an example I have some
>     > templates that are either created on SSD or magnetic storage. The
> template
>     > has a storage tag associated with it and then I assigned the
> appropriate
>     > storage tag to the primary storage.
>     >
>     >         Regards,
>     >         Marty Godsey
>     >
>     >         -----Original Message-----
>     >         From: Tutkowski, Mike [mailto:Mike.Tutkowski@netapp.com]
>     >         Sent: Thursday, September 8, 2016 7:16 PM
>     >         To: dev@cloudstack.apache.org
>     >         Subject: Re: storage affinity groups
>     >
>     >         If one doesn't already exist, you can write a custom storage
>     > allocator to handle this scenario.
>     >
>     >         > On Sep 8, 2016, at 4:25 PM, Yiping Zhang <
> yzhang@marketo.com>
>     > wrote:
>     >         >
>     >         > Hi,  Devs:
>     >         >
>     >         > We all know how (anti)-host affinity group works in
> CloudStack,
>     > I am wondering if there is a similar concept for (anti)-storage
> affinity
>     > group?
>     >         >
>     >         > The use case is as this:  in a setup with just one
> (somewhat)
>     > unreliable primary storage, if the primary storage is off line, then
> all VM
>     > instances would be impacted. Now if we have two primary storage
> volumes for
>     > the cluster, then when one of them goes offline, only half of VM
> instances
>     > would be impacted (assuming the VM instances are evenly distributed
> between
>     > the two primary storage volumes).  Thus, the (anti)-storage affinity
> groups
>     > would make sure that instance's disk volumes are distributed among
>     > available primary storage volumes just like (anti)-host affinity
> groups
>     > would distribute instances among hosts.
>     >         >
>     >         > Does anyone else see the benefits of anti-storage affinity
>     > groups?
>     >         >
>     >         > Yiping
>     >
>     >
>     >
>     >
>     >
>
>
>

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