Re: New Option for Extra EBS Volumes?

From: Jacob Barhak <no email>
Date: Fri, 4 Oct 2013 14:49:32 -0400

Hi Lyn,

You have me as a second for improving sharing and EBS handling. I had difficulties with these issues.

I know Justin had a thread in github discussing improving the NFS share command. Yet there was little progress there. Here is the link:
https://github.com/jtriley/StarCluster/issues/44

This may not be the full solution you are looking for, yet there may be parts there you are looking for.

I hope someone moves in that direction next version.

        Jacob

Sent from my iPhone

On Oct 4, 2013, at 2:26 PM, Lyn Gerner <schedulerqueen_at_gmail.com> wrote:

> Hi Developers, All,
>
> I am struggling operationally with the snapshots and volumes that starcluster creates when I attach extra (non-root) EBS volumes to the cluster nodes that I launch.
>
> I have read everything I can find that's relevant in the mailing list -- in particular, this -- and understand that this is just how it's designed to work.
>
> As background for anyone unfamiliar with this, currently, starcluster only will NFS-share volumes that are specified in the cluster template. It doesn't share volumes that are already existing devices in an AMI.
>
> I have also experimented with the Delete on Termination setting for volumes associated with my AMIs. The volume has to be built into an AMI (as a block device), and has to be attached to an instance when it's terminated, in order for the deletion to take place.
>
> Starcluster terminate operation umounts devices and detaches volumes before terminating cluster instances. This negates the Delete on Termination operation for such volumes.
>
> I would like to be able to have starcluster share such additional volumes that are already present as block devices in the AMI. This would allow me to flip the bit in the AMI that would cause delete-on-termination for the volume.
>
> Could we have a new option, basically a "--share-also=<dev>:<mount_point>"? I think you would also need to *not* detach such extra volumes (though you'd of course umount them) in the cluster termination process, in order for the Delete-on-Termination setting to take effect.
>
> I acknowledge that it's more complex than I've described, because the "volumes" attached to the instances are actually snapshots, in the way that starcluster (and AWS) functions. I haven't found anything in AWS-land that auto-deletes snapshots on termination.
>
> This is all pretty confusing and frustrating.
>
> I'd appreciate it if Justin and others would discuss the feasibility of such a "--share-also" function, any reasons why it could not work correctly, or would foul up the Starcluster design or operations.
>
> And if anyone has overcome the operational issue of volumes and snapshots piling up -- that is, if you've automated recognition and deletion of temporary copies of volumes and snapshopts -- I'd love to hear about your approach.
>
> Thanks to all,
> Lyn
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Received on Fri Oct 04 2013 - 14:49:44 EDT