Re: [SPDK] Snapshot issue when deleting last clone

Re: [SPDK] Snapshot issue when deleting last clone

[Harris, James R]

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That makes sense. Thanks for the explanation.

Jim

Sent from my iPhone

> On Dec 12, 2018, at 12:00 AM, Szwed, Maciej <maciej.szwed(a)intel.com> wrote:
> 
> The issue was that volume was listed by get_bdevs as not a snapshot, but it was actually read only, so it still behaves as a snapshot. Client is tracking volumes and snapshots using only output from get_bdevs and that fails in this case.
> 
> Maciek
> 
> -----Original Message-----
> From: SPDK [mailto:spdk-bounces(a)lists.01.org] On Behalf Of Harris, James R
> Sent: Monday, December 10, 2018 5:39 PM
> To: Storage Performance Development Kit <spdk(a)lists.01.org>
> Subject: Re: [SPDK] Snapshot issue when deleting last clone
> 
> Hi Maciek,
> 
> Can you describe the issue in more detail?  Meaning what was the impact of removing the snapshot from the snapshots TAILQ when its number of clones reached 0?
> 
> In general I agree that we should not implicitly make the volume RW after its last clone is removed.
> 
> Thanks,
> 
> -Jim
> 
> 
> On 12/10/18, 3:53 AM, "SPDK on behalf of Szwed, Maciej" <spdk-bounces(a)lists.01.org on behalf of maciej.szwed(a)intel.com> wrote:
> 
>    Hi,
>    One of SPDK clients found issue with deleting last clone of snapshot. After investigation I found out that in such case is we remove the snapshot from snapshots list in function _spdk_bs_blob_list_remove(), but the volume remains read-only as it was still a snapshot.
>    We should correct this, but what would be the appropriate way? Should we NOT remove the snapshot from snapshots list (makes more sense to me), or should we convert it to normal volume by making it RW (that options may confuse user that created snapshot, which was later converted to normal volume and now user cannot create clone from it anymore).
>    Let me know what do you think about it.
> 
>    Thanks,
>    Maciek
> 
> 
>    _______________________________________________
>    SPDK mailing list
>    SPDK(a)lists.01.org
>    https://lists.01.org/mailman/listinfo/spdk
> 
> 
> _______________________________________________
> SPDK mailing list
> SPDK(a)lists.01.org
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Re: [SPDK] Snapshot issue when deleting last clone

[Szwed, Maciej]

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The issue was that volume was listed by get_bdevs as not a snapshot, but it was actually read only, so it still behaves as a snapshot. Client is tracking volumes and snapshots using only output from get_bdevs and that fails in this case.

Maciek

-----Original Message-----
From: SPDK [mailto:spdk-bounces(a)lists.01.org] On Behalf Of Harris, James R
Sent: Monday, December 10, 2018 5:39 PM
To: Storage Performance Development Kit <spdk(a)lists.01.org>
Subject: Re: [SPDK] Snapshot issue when deleting last clone

Hi Maciek,

Can you describe the issue in more detail?  Meaning what was the impact of removing the snapshot from the snapshots TAILQ when its number of clones reached 0?

In general I agree that we should not implicitly make the volume RW after its last clone is removed.

Thanks,

-Jim


On 12/10/18, 3:53 AM, "SPDK on behalf of Szwed, Maciej" <spdk-bounces(a)lists.01.org on behalf of maciej.szwed(a)intel.com> wrote:

    Hi,
    One of SPDK clients found issue with deleting last clone of snapshot. After investigation I found out that in such case is we remove the snapshot from snapshots list in function _spdk_bs_blob_list_remove(), but the volume remains read-only as it was still a snapshot.
    We should correct this, but what would be the appropriate way? Should we NOT remove the snapshot from snapshots list (makes more sense to me), or should we convert it to normal volume by making it RW (that options may confuse user that created snapshot, which was later converted to normal volume and now user cannot create clone from it anymore).
    Let me know what do you think about it.
    
    Thanks,
    Maciek
    
    
    _______________________________________________
    SPDK mailing list
    SPDK(a)lists.01.org
    https://lists.01.org/mailman/listinfo/spdk
    

_______________________________________________
SPDK mailing list
SPDK(a)lists.01.org
https://lists.01.org/mailman/listinfo/spdk

Re: [SPDK] Snapshot issue when deleting last clone

[Harris, James R]

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Hi Maciek,

Can you describe the issue in more detail?  Meaning what was the impact of removing the snapshot from the snapshots TAILQ when its number of clones reached 0?

In general I agree that we should not implicitly make the volume RW after its last clone is removed.

Thanks,

-Jim


On 12/10/18, 3:53 AM, "SPDK on behalf of Szwed, Maciej" <spdk-bounces(a)lists.01.org on behalf of maciej.szwed(a)intel.com> wrote:

    Hi,
    One of SPDK clients found issue with deleting last clone of snapshot. After investigation I found out that in such case is we remove the snapshot from snapshots list in function _spdk_bs_blob_list_remove(), but the volume remains read-only as it was still a snapshot.
    We should correct this, but what would be the appropriate way? Should we NOT remove the snapshot from snapshots list (makes more sense to me), or should we convert it to normal volume by making it RW (that options may confuse user that created snapshot, which was later converted to normal volume and now user cannot create clone from it anymore).
    Let me know what do you think about it.
    
    Thanks,
    Maciek
    
    
    _______________________________________________
    SPDK mailing list
    SPDK(a)lists.01.org
    https://lists.01.org/mailman/listinfo/spdk
    

[SPDK] Snapshot issue when deleting last clone

[Szwed, Maciej]

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Hi,
One of SPDK clients found issue with deleting last clone of snapshot. After investigation I found out that in such case is we remove the snapshot from snapshots list in function _spdk_bs_blob_list_remove(), but the volume remains read-only as it was still a snapshot.
We should correct this, but what would be the appropriate way? Should we NOT remove the snapshot from snapshots list (makes more sense to me), or should we convert it to normal volume by making it RW (that options may confuse user that created snapshot, which was later converted to normal volume and now user cannot create clone from it anymore).
Let me know what do you think about it.

Thanks,
Maciek