On Mon, Nov 16, 2015 at 4:36 AM, Boris <[email protected]> wrote:

> I should have been more specific, in my case I see the problem with zvols:
> the first snapshot has a non-zero block, the next snapshot has the block
> overwrite with zeros, but the stream lacks the free record. The zvol is
> ~1.2T, 64k block size, sparse, has lz4 compression on.
>

In that case I don't think your problem is related to the bug I mentioned,
which only has to do with objects that have been reallocated.  You must be
seeing a different issue.  We also can not reproduce your issue with a
simple test case.

--matt


>
> Typos courtesy of my iPhone
>
> On Nov 15, 2015, at 12:25 PM, Matthew Ahrens <[email protected]> wrote:
>
> btw, here is the bug you're asking about:
> https://www.illumos.org/issues/6370
>
> --matt
>
> On Sun, Nov 15, 2015 at 9:24 AM, Matthew Ahrens <[email protected]>
> wrote:
>
>> We have a fix for this that we need to upstream.  We are waiting on code
>> reviews for another change to send/receive:
>>
>> https://github.com/openzfs/openzfs/pull/23
>> 6393 zfs receive a full send as a clone
>>
>> I'll probably stop waiting soon and RTI it, then we get get our fix for
>> this in.
>>
>> --matt
>>
>> On Sun, Nov 15, 2015 at 8:37 AM, Boris <[email protected]> wrote:
>>
>>> Hi, guys,
>>>
>>>
>>> I've been looking an issue where sometimes, after non-zero data blocks
>>> are overwritten with zero blocks with compression on, the corresponding
>>> incremental send stream does not include the FREE record for those blocks.
>>> The zdb -ddddddd output seems to indicate that the blocks in question have
>>> never been written (the offsets for them are not listed in the output).
>>>
>>>
>>> This looks like the issue addressed by
>>>
>>>
>>> commit a4069eef2e403a3b2a307b23b7500e2adc6ecae5
>>>
>>> Author: Prakash Surya <[email protected]>
>>>
>>> Date:   Fri Mar 27 13:03:22 2015 +1100
>>>
>>>
>>>     Illumos 5695 - dmu_sync'ed holes do not retain birth time
>>>
>>>
>>> but I certainly do have that commit. I have experimented with
>>> overwriting blocks at different offsets, ranges of blocks spanning L1 and
>>> L2 block pointers, but I cannot reproduce the issue.
>>>
>>>
>>> Any suggestions for directions to look ? Perhaps for a way to shape the
>>> block tree such that this problem could arise ?
>>>
>>>
>>> Best regards,
>>>
>>> Boris.
>>>
>>> _______________________________________________
>>> developer mailing list
>>> [email protected]
>>> http://lists.open-zfs.org/mailman/listinfo/developer
>>>
>>>
>>
>
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