Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-29 Thread Dan Genin
On 10/28/2014 02:50 PM, John Griffith wrote: On Tue, Oct 28, 2014 at 12:37 PM, Dan Genin daniel.ge...@jhuapl.edu mailto:daniel.ge...@jhuapl.edu wrote: Great, thank you, Duncan. I will then proceed with the shared volume group. Dan On 10/28/2014 02:06 PM, Duncan Thomas

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Dan Genin
Duncan, I don't think it's possible to have multiple volume groups using the same physical volume[1]. In fact, counter-intuitively (at least to me) the nesting actually goes the other way with multiple physical volumes comprising a single volume group. The LVM naming scheme actually makes more

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Dean Troyer
On Tue, Oct 28, 2014 at 9:27 AM, Dan Genin daniel.ge...@jhuapl.edu wrote: So this brings us back to the original proposal of having separate backing files for Cinder and Nova which Dean thought might take too much space. Between Cinder, Nova and Swift (and Ceph, etc) everybody wants some

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Duncan Thomas
Hi Dan You're quite right, the nesting isn't as I thought it was, sorry to mislead you. It isn't a show stopper, it just makes testing some proposed useful functionality slightly harder. If nova were to namespace its volumes (e.g. start all the volume names with nova-*) then that would allow the

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Dan Genin
On 10/28/2014 11:56 AM, Dean Troyer wrote: On Tue, Oct 28, 2014 at 9:27 AM, Dan Genin daniel.ge...@jhuapl.edu mailto:daniel.ge...@jhuapl.edu wrote: So this brings us back to the original proposal of having separate backing files for Cinder and Nova which Dean thought might take too

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Dan Genin
On 10/28/2014 12:47 PM, Duncan Thomas wrote: Hi Dan You're quite right, the nesting isn't as I thought it was, sorry to mislead you. It isn't a show stopper, it just makes testing some proposed useful functionality slightly harder. If nova were to namespace its volumes (e.g. start all the

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Duncan Thomas
Cinder volumes are always (unless you go change the default) in the form: volume-uuid, and since the string 'volume-' is never a valid uuid, then I think we can work around nova volumes fine when we come to write our tests. Sorry for the repeated circling on this, but I think I'm now happy.

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Duncan Thomas
On 28 October 2014 18:01, Dan Genin daniel.ge...@jhuapl.edu wrote: Changing Nova disk names is a lng shot. It's likely I will be doing something else by the time that gets merged:) So we are left with the two options of 1) using a shared volume group and, thus, complicating life for

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread Dan Genin
Great, thank you, Duncan. I will then proceed with the shared volume group. Dan On 10/28/2014 02:06 PM, Duncan Thomas wrote: Cinder volumes are always (unless you go change the default) in the form: volume-uuid, and since the string 'volume-' is never a valid uuid, then I think we can work

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-28 Thread John Griffith
On Tue, Oct 28, 2014 at 12:37 PM, Dan Genin daniel.ge...@jhuapl.edu wrote: Great, thank you, Duncan. I will then proceed with the shared volume group. Dan On 10/28/2014 02:06 PM, Duncan Thomas wrote: Cinder volumes are always (unless you go change the default) in the form: volume-uuid,

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-23 Thread John Griffith
On Tue, Oct 21, 2014 at 2:48 PM, Dan Genin daniel.ge...@jhuapl.edu wrote: So then it is probably best to leave existing Cinder LVM code in lib/cinder_backends/lvm alone and create a similar set of lvm scripts for Nova, perhaps in lib/nova_backends/lvm? Dan On 10/21/2014 03:10 PM, Duncan

[openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-21 Thread Dan Genin
Hello, I would like to add to DevStack the ability to stand up Nova with LVM ephemeral storage. Below is a draft of the blueprint describing the proposed feature. Suggestions on architecture, implementation and the blueprint in general are very welcome. Best, Dan

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-21 Thread Preston L. Bannister
As a side-note, the new AWS flavors seem to indicate that the Amazon infrastructure is moving to all ECS volumes (and all flash, possibly), both ephemeral and not. This makes sense, as fewer code paths and less interoperability complexity is a good thing. That the same balance of concerns should

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-21 Thread Duncan Thomas
Sharing the vg with cinder is likely to cause some pain testing proposed features cinder reconciling backend with the cinder db. Creating a second vg sharing the same backend pv is easy and avoids all such problems. Duncan Thomas On Oct 21, 2014 4:07 PM, Dan Genin daniel.ge...@jhuapl.edu wrote:

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-21 Thread Dan Genin
Did you mean EBS? I thought it was generally hard to get the same kind of performance from block storage that local ephemeral storage provides but perhaps Amazon has found a way. Life would certainly be much simpler with a single ephemeral backend. Storage pools

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-21 Thread Dan Genin
Do you mean that Cinder will be confused by Nova's volumes in its volume group? Yeah, sure that would be similarly easy to implement. Thank you for the suggestion! Dan On 10/21/2014 03:10 PM, Duncan Thomas wrote: Sharing the vg with cinder is likely to cause some pain testing proposed

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-21 Thread Preston L. Bannister
Yes, I meant EBS not ECS. Too many similar acronyms... The thing about the Amazon folk is that they collect a lot of metrics, and pretty much do everything on a fairly empirical basis. This is a huge advantage. Starting thinking about what I could with good metrics and building on the performance

Re: [openstack-dev] [devstack] Enable LVM ephemeral storage for Nova

2014-10-21 Thread Dan Genin
So then it is probably best to leave existing Cinder LVM code in lib/cinder_backends/lvm alone and create a similar set of lvm scripts for Nova, perhaps in lib/nova_backends/lvm? Dan On 10/21/2014 03:10 PM, Duncan Thomas wrote: Sharing the vg with cinder is likely to cause some pain testing