Re: [SPDK] Removing bs_dev

Re: [SPDK] Removing bs_dev

[Walker, Benjamin]

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On Wed, 2018-07-25 at 04:44 +0000, Szwed, Maciej wrote:
> Hi,
> I was examining possibility of removing bs_dev layer from blobstore. As this
> would simplify code for basic blob/lvol usage, in case of snapshots and clones
> it would require whole new approach. Currently bs_dev layer is a basic
> mechanism for snapshots and clones interactions. I was thinking about some
> other ways we could build that relations w/o bs_dev, but I couldn’t find any
> good mechanism which would be simpler (or at least less complicated) than the
> current one. Therefore I don’t think that removing bs_dev is a good idea. If
> somebody have different thoughts on that or some ideas please let me know.


If removing the bs_dev from the clone/snapshot path doesn't result in a major
simplification, then it isn't worth doing. I thought that it might, since
blob_bs_dev.c could be removed entirely. But you still do need some abstraction
for handling what to do when a blob is thin provisioned and needs to return
zeroes, so maybe that negates any other simplifications. We can leave it low
priority and think about it for awhile.

Thanks,
Ben

Re: [SPDK] Removing bs_dev

[Yang, Ziye]

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Hi Maciek,

I have the same thought. Actually, bs_dev is not a real bdev. At least, it makes some ambiguous understanding. I think that Jim and Ben may have some ideas.


Best Regards
Ziye Yang

From: SPDK [mailto:spdk-bounces(a)lists.01.org] On Behalf Of Szwed, Maciej
Sent: Wednesday, July 25, 2018 12:45 PM
To: Storage Performance Development Kit <spdk(a)lists.01.org>
Subject: [SPDK] Removing bs_dev

Hi,
I was examining possibility of removing bs_dev layer from blobstore. As this would simplify code for basic blob/lvol usage, in case of snapshots and clones it would require whole new approach. Currently bs_dev layer is a basic mechanism for snapshots and clones interactions. I was thinking about some other ways we could build that relations w/o bs_dev, but I couldn't find any good mechanism which would be simpler (or at least less complicated) than the current one. Therefore I don't think that removing bs_dev is a good idea. If somebody have different thoughts on that or some ideas please let me know.

Thanks,
Maciek



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[SPDK] Removing bs_dev

[Szwed, Maciej]

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Hi,
I was examining possibility of removing bs_dev layer from blobstore. As this would simplify code for basic blob/lvol usage, in case of snapshots and clones it would require whole new approach. Currently bs_dev layer is a basic mechanism for snapshots and clones interactions. I was thinking about some other ways we could build that relations w/o bs_dev, but I couldn't find any good mechanism which would be simpler (or at least less complicated) than the current one. Therefore I don't think that removing bs_dev is a good idea. If somebody have different thoughts on that or some ideas please let me know.

Thanks,
Maciek



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