[Openstack] Cinder vs Swift architecture

Adam Lawson alawson at aqorn.com
Mon Oct 5 18:49:42 UTC 2015


Hi Ayushi,

The quick and dirty explanation:

Cinder can have different back-ends. With a Linux approach, Cinder uses
LVM2 to carve up local disks so they can be consumed by virtual machines
that need to attach to a volume (for data or to boot). A common way for
VM's to consume these volumes is via iSCSI (see iscsi targets and
initiators for more details). The end result is the VM's talk to the
volumes rather than talking to Cinder to get to the data.

Swift also carves up local disks and stores data on them but the data
itself is accessed using an API (similar to dropbox). No exceptions. VM's
don't mount the data on the back-end the way they do with Cinder-managed
volumes, but object storage is instead leveraged for things like user
storage, enterprise department data storage (similar to
Accounting/Marketing/IT share drive) or as a back-end for services that
need a safe place to store files for future use like Glance, Cinder
backups, Barbican, etc.

In terms of how the disks are consumed on a local machine, Cinder allows
the VM to mount and format the drive/volume then use however it wants to.
Swift formats it and presents a pre-formatted volume so you can just drop a
file and get it later.

Does that help at all?

//adam




*Adam Lawson*

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On Mon, Oct 5, 2015 at 12:26 AM, Abhishek Shrivastava <
abhishek at cloudbyte.com> wrote:

> Hi Ayushi,
>
> If you had not gone through this link, then please have a look and let us
> know if it is useful:
>
>    -
>    http://www.computerweekly.com/feature/OpenStack-storage-Cinder-and-Swift-explained
>
>
> On Mon, Oct 5, 2015 at 12:27 PM, Ayushi Kumar <ayushi.03march at gmail.com>
> wrote:
>
>> Hi,
>>
>> Even after going through number of links and documents online , I am
>> unable to understand that exactly
>>
>>    - * how file storage , cinder and swift work if I talk in terms of a
>>    personal computer which has openstack insatlled on it.*
>>
>> Can anyone please explain that if I have a hard drive then
>>
>>    - * how cinder uses it for block storage and and how swift uses it
>>    for object storage.*
>>
>> Though the difference between the two storage is clear ,I am unable to
>> understand how the same hard drive is used for both object storage and
>> block storage .
>>
>> Regards
>> Ayushi
>>
>> _______________________________________________
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>>
>
>
> --
>
>
> *Thanks & Regards,*
> *Abhishek*
> *Cloudbyte Inc. <http://www.cloudbyte.com>*
>
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>
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