zfs send from an ancient system

[Daniel O'Connor]

> On 7 Dec 2020, at 23:06, Daniel O'Connor <darius at dons.net.au> wrote:
>> On 7 Dec 2020, at 18:18, Daniel O'Connor <darius at dons.net.au> wrote:
>> I am sure I have done this in the past from this machine, unfortunately I don't have the receiving machine any more as it got repurposed.
> 
> I created a new test FS on the 8.2 machine with a single file in it and it reproduces the problem.
> 
> I did some tests with an md(4) backed zpool and it works on 11.3-RELEASE-p5 and fails on 12.0-RELEASE-p10.

I did a bisect and found the commit:
commit 46cdbe4a7a57c13eb35e99a5abea862ef346524f (HEAD)
Author: mmacy <mmacy at FreeBSD.org>
Date:   Sun Aug 12 00:45:53 2018 +0000

    MFV/ZoL: Implement large_dnode pool feature

    commit 50c957f702ea6d08a634e42f73e8a49931dd8055
    Author: Ned Bass <bass6 at llnl.gov>
    Date:   Wed Mar 16 18:25:34 2016 -0700

        Implement large_dnode pool feature
...
Notes:
    svn path=/head/; revision=337669

I did try creating a pool with no features enabled (zpool create -d ...) but it still failed.

> Also, it appears I can 'launder' the send through the 11.3 machine, ie recv on it then send to the 12.2 system and it works.
> 
> Tested with the following:
> truncate -s 100M /tmp/zfs.1
> sudo mdconfig -t vnode -f /tmp/zfs.1
> sudo zpool create testtank /dev/md0
> curl http://www.gsoft.com.au/~doconnor/test.zfssend.gz | gzip -d | sudo zfs recv -vd testtank
> sudo zpool destroy testtank
> sudo mdconfig -u md0 -d
> rm /tmp/zfs.1
> 
> --
> Daniel O'Connor
> "The nice thing about standards is that there
> are so many of them to choose from."
> -- Andrew Tanenbaum
> 

--
Daniel O'Connor
"The nice thing about standards is that there
are so many of them to choose from."
 -- Andrew Tanenbaum