Cinder volume as file system

asked 2018-05-09 02:16:31 -0600

mike11 gravatar image

Hi Everyone,

Is there a way to create a volume drive with Cinder that is not an actual disk? I hope that this is clear, but what i would like to do is to write data dynamically to a local file which will be persistent as a drive. For example, using NFS we write to a local file which is then written to the distant FS. Here i would like to write to a local file and never upload it to the network. I was thinking of using SambaFS for example, but i could not find a proper procedure or where do i actually download the driver. And, i am also not sure that it would work with Sambafs. I would appreciate any input in this.

Thank you kindly, Michael

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answered 2018-05-09 06:26:02 -0600

updated 2018-05-09 06:51:39 -0600

A volume is a disk. You can attach it to an instance, put a file system on it and create a file on that file system that is then persistent. To the instance, a volume looks like a block device, which you may call drive, or disk, or LUN etc. It may well be implemented as something else than a disk, e.g. a logical volume or a Ceph device, but I believe your question is not about the implementation. In short, if I understand your question correctly, the answer is no.

Apart from Cinder, you can use Swift or Manila for persistent storage. Manila manages remote filesystems, not disks, which reside on Windows or NFS shares and many other backends. Perhaps this is what you are looking for? Swift is an altogether different beast. A Swift object neither looks like a disk, nor a filesystem, nor a file, and is accessed using HTTP.

Admittedly, it’s not clear to me what exactly you want to achieve and why volumes are not a solution to your problem.

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Thanks Bernd for you answer! The solution of Manila was something that i was looking at as well but the issue there is that i do not need to share the files which is why i think that this would not fit for security reason and that it will also use more resources then needed (an additional service).

mike11 gravatar imagemike11 ( 2018-05-14 02:52:05 -0600 )edit

as for why we would like not to have another block storage is that we are short on space and we cannot allocate all of potential space for the volume. I would like to dynamically allocate the space. Does anyone have any other ideas?

mike11 gravatar imagemike11 ( 2018-05-14 02:52:19 -0600 )edit

Hi Michael, I am not sure if the my idea is well suited for your needs, but why not using an external disk array, if security and persistence is a concern. Is this going to be a private cloud, meaning hosted inside your organization, or a public cloud?

cinderela gravatar imagecinderela ( 2018-05-14 07:18:43 -0600 )edit

Hi cinderela, This is a local compute that the VM is running on and i cannot connect to it an external array.

mike11 gravatar imagemike11 ( 2018-05-14 07:33:14 -0600 )edit

I understand that you have the requirement of making a single file persistent, while the filesystem as a whole is ephemeral. Is that correct? If so, there is no solution in OpenStack as far as I know. You need to create that file on a persistent filesystem, which can either be a volume or a share.

Bernd Bausch gravatar imageBernd Bausch ( 2018-05-14 18:33:19 -0600 )edit

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Asked: 2018-05-09 02:16:31 -0600

Seen: 468 times

Last updated: May 09 '18