Is "reconstruct -V max..." needed when upgrading from 2.5.10 to 3.0.7?

Nic Bernstein nic at onlight.com
Tue Jul 31 17:26:26 EDT 2018


On 07/31/2018 02:32 PM, Savvas Karagiannidis wrote:
> Hi Nic,
> as far as I know there are currently a couple of nasty open issues 
> when upgrading old mailboxes, created from earlier versions of cyrus, 
> that have not been upgraded to v13 index using reconstruct. These 
> issues are:
>
> https://github.com/cyrusimap/cyrus-imapd/issues/2171
> https://github.com/cyrusimap/cyrus-imapd/issues/2208
>
> The main problem is frequent crashes with error message "assertion 
> failed" when accessing these mailboxes.
>
> In issue #2208 a reconstruct command was proposed as a workaround:
> |reconstruct -G -V max [mailboxname]|
>
> Note that -G parameter seems necessary, otherwise the problem persists...
>
> Note also, that this should be done while still in version 2.5.x! The 
> behavior of version 3.x reconstruct is not the same and you will not 
> have the same results.
>
> As for the cyrdump you mention, it would be better if you compared the 
> results before running reconstruct and after that.
> I guess what you would see is that the uidlist before would probably 
> be in the range 6 - 9 (or you'd see a crash). cyrus 3.0.x considers 
> that part of the index corrupt so simply cannot access those uids 
> (1-5). Reconstruct detects this issue and what it does is that 
> *reappends *those "newly found" messages, giving them a new uid, so 
> that's what uids 10-14 probably really are. Note that this causes 
> these messages to appear unread, since they have no flags (not 
> something you want for your clients' mailboxes).
>
> Bron mentioned something about this bug in the cyrus devel list a few 
> days ago:
> https://lists.andrew.cmu.edu/pipermail/cyrus-devel/2018-July/thread.html#4313
> but I didn't see any related commit or anything mentioned in the above 
> issues, so I'm not sure if there is a fix at the moment...

[Cross posting to cyrus-devel, as am now dumping core]

Savvas,
Thanks for your response.  I think, however, that we've already tackled 
the issue of assert failures in reconstruct.  If you follow the entire 
thread of the message you linked to, Bron's message from the other day, 
he was actually writing to me, and his patch, referenced with a commit, 
within that message, worked just fine for me, as addressed in my follow up:
https://lists.andrew.cmu.edu/pipermail/cyrus-devel/2018-July/004315.html

But I can see that you're correct about the cyrdump issue.  That's a 
real mess.  Here's the top of a cyrdump from the old host, running 2.5.10:

    onlight at mail:~$ sudo su cyrus -c "/usr/lib/cyrus/bin/cyrdump user.onlight" | head -12
    Content-Type: multipart/related; boundary="dump-10426-1533070392-23406623"

    --dump-10426-1533070392-23406623
    Content-Type: text/xml
    IMAP-Dump-Version: 0

    <imapdump uniqueid="710a47ca47ebc676">
       <mailbox-url>imap://mail.ahwi.us/user.onlight</mailbox-url>
       <incremental-uid>0</incremental-uid>
       <nextuid>10</nextuid>

       <uidlist>1 2 3 4 5 6 7 9 </uidlist>

which comports with the existing mailbox directory:

    onlight at mail:~$ sudo ls /var/spool/cyrus/mail/I/user/onlight/
    1.  2.  3.  4.  5.  6.  7.  8.  9.  cyrus.annotations  cyrus.cache  cyrus.header  cyrus.index  Drafts  Sent  Spam  Trash

And here's what it looks like after reconstructing on the new server:

    root at newmail:~# ls /var/spool/cyrus/mail/I/user/onlight/
    10.  11.  12.  13.  14.  6.  7.  8.  9.  cyrus.annotations  cyrus.cache  cyrus.header  cyrus.index  Drafts  Sent  Spam  Trash

But I cannot even run cyrdump on the new mailbox now, I keep dumping 
core with a Floating Point error:

    root at newmail:~# /usr/lib/cyrus/bin/cyrdump user/onlight
    Content-Type: multipart/related; boundary="dump-27702-1533070740-1079351705"

    --dump-27702-1533070740-1079351705
    Content-Type: text/xml
    IMAP-Dump-Version: 0

    <imapdump uniqueid="710a47ca47ebc676">
       <mailbox-url>imap://newmail.ahwi.us/user.onlight</mailbox-url>
       <incremental-uid>0</incremental-uid>
       <nextuid>15</nextuid>

       <uidlist>6 7 9 10 11 12 13 14 </uidlist>

       <flags>
    Floating point exception (core dumped)

Here's a backtrace from gdb:

    Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
    Core was generated by `/usr/lib/cyrus/bin/cyrdump user/onlight'.
    Program terminated with signal SIGFPE, Arithmetic exception.
    #0  0x00007fcbc1057955 in hash_lookup (key=key at entry=0x7ffd75ae4610 "systemflags",
         table=table at entry=0x7fcbc1894e30 <attrs_by_name>) at lib/hash.c:159
    159     lib/hash.c: No such file or directory.
    (gdb) bt
    #0  0x00007fcbc1057955 in hash_lookup (key=key at entry=0x7ffd75ae4610 "systemflags",
         table=table at entry=0x7fcbc1894e30 <attrs_by_name>) at lib/hash.c:159
    #1  0x00007fcbc1636822 in search_attr_find (name=<optimized out>) at imap/search_expr.c:2465
    #2  0x000055c087d5a694 in systemflag_match (flag=1) at imap/cyrdump.c:149
    #3  0x000055c087d5a9dd in dump_me (data=<optimized out>, rock=0x7ffd75ae68e0) at imap/cyrdump.c:209
    #4  0x00007fcbc16164c3 in find_cb (rockp=rockp at entry=0x7ffd75ae6820,
         key=key at entry=0x7fcbc1aa1a28 <error: Cannot access memory at address 0x7fcbc1aa1a28>, keylen=keylen at entry=12,
         data=data at entry=0x7fcbc1aa1a38 <error: Cannot access memory at address 0x7fcbc1aa1a38>, datalen=<optimized out>)
         at imap/mboxlist.c:2410
    #5  0x00007fcbc131f553 in myforeach (db=0x55c0894b2610, prefix=0x7ffd75ae5fb0 "user.onlight", prefixlen=0,
         goodp=0x7fcbc16162c0 <find_p>, cb=0x7fcbc1616390 <find_cb>, rock=0x7ffd75ae6820, tidptr=<optimized out>)
         at lib/cyrusdb_skiplist.c:1177
    #6  0x00007fcbc16141cd in mboxlist_find_category (rock=rock at entry=0x7ffd75ae6820,
         prefix=prefix at entry=0x7ffd75ae5fb0 "user.onlight", len=len at entry=0) at imap/mboxlist.c:2685
    #7  0x00007fcbc1614b2c in mboxlist_do_find (rock=rock at entry=0x7ffd75ae6820, patterns=patterns at entry=0x55c0894b26f0)
         at imap/mboxlist.c:2877
    #8  0x00007fcbc1619fe6 in mboxlist_findallmulti (namespace=<optimized out>, patterns=0x55c0894b26f0, isadmin=<optimized out>,
         userid=0x0, auth_state=<optimized out>, proc=<optimized out>, rock=0x7ffd75ae68e0) at imap/mboxlist.c:2942
    #9  0x000055c087d5a4bd in main (argc=2, argv=<optimized out>) at imap/cyrdump.c:119

I'll note, too, that the behavior of reconstruct, with regards to those 
low numbered UIDs, is totally inconsistent.  Here's a re-run on the same 
mailbox, after re-rsyncing (with --delete option) from the original server:

    root at newmail:~# su cyrus -c "/usr/lib/cyrus/bin/reconstruct -V max user/onlight"
    user.onlight: update uniqueid from header (null) => 710a47ca47ebc676
    user.onlight updating quota_mailbox_used: 10715 => 3910
    user.onlight: updating exists 8 => 3
    user.onlight: updating sync_crc 2250269913 => 1705867986
    user/onlight
    Repacked user/onlight to version 13
    root at newmail:~# ls -l /var/spool/cyrus/mail/I/user/onlight/
    total 76
    -rw------- 1 cyrus mail  2924 Mar 27  2008 1.
    -rw------- 1 cyrus mail   748 Mar 27  2008 2.
    -rw------- 1 cyrus mail   804 Jul 15  2008 3.
    -rw------- 1 cyrus mail  1137 Oct  2  2009 4.
    -rw------- 1 cyrus mail  1192 Apr 22  2012 5.
    -rw------- 1 cyrus mail  1423 Sep 19  2016 6.
    -rw------- 1 cyrus mail  1743 Dec 22  2016 7.
    -rw------- 2 cyrus mail  1357 Jun  1  2017 8.
    -rw------- 1 cyrus mail   744 Jun  1  2017 9.
    -rw------- 1 cyrus mail   336 Mar  1  2017 cyrus.annotations
    -rw------- 1 cyrus mail 10276 Jul 31 15:54 cyrus.cache
    -rw------- 1 cyrus mail   165 Feb 28  2017 cyrus.header
    -rw------- 1 cyrus mail  1064 Jul 31 16:16 cyrus.index
    drwx------ 2 cyrus mail  4096 Nov 30  2017 Drafts
    drwx------ 2 cyrus mail  4096 Nov 30  2017 Sent
    drwx------ 2 cyrus mail  4096 Nov 30  2017 Spam
    drwx------ 2 cyrus mail  4096 Nov 30  2017 Trash

So now it's just ignoring UIDs 1-6, and claiming the mailbox has just 3 
messages.

Color me confused.

Honestly, I am not sure how anyone is managing large upgrades from 2.5 
to 3.0?  Not being able to reliably bring the existing message store up 
to the necessary level is quite unsettling.

Cheers,
     -nic

>
> Hope this helps,
> Regards,
> Savvas Karagiannidis
>
> On Tue, Jul 31, 2018 at 6:43 PM Nic Bernstein <nic at onlight.com 
> <mailto:nic at onlight.com>> wrote:
>
>     Friends,
>     I'm preparing for a couple of belated 2.5.X to 3.0.X upgrades, and
>     have a question about how necessary it is to run "reconstruct -V
>     max" on the mailstore.  Both systems are currently running 2.5.10,
>     and are already at index version 13.  However, when performing
>     "reconstruct -V max" on one, on a new 3.0.7 (with patches) system,
>     I see this:
>
>         root at newmail:~# /usr/lib/cyrus/bin/reconstruct -V max user/onlight
>         user.onlight uid 1 rediscovered - appending
>         user.onlight uid 2 rediscovered - appending
>         user.onlight uid 3 rediscovered - appending
>         user.onlight uid 4 rediscovered - appending
>         user.onlight uid 5 rediscovered - appending
>         user/onlight
>         Repacked user/onlight to version 13
>
>     The last line can be ignored, as it's really a noop.  The
>     "rediscovered - appending" stuff is what catches my eye. However,
>     once the reconstruct is complete, here's what the mailbox looks like:
>
>         root at newmail:/var/spool/cyrus/mail/I/user/onlight# /usr/lib/cyrus/bin/cyrdump user/onlight
>         Content-Type: multipart/related; boundary="dump-27466-1533049817-351841533"
>
>         --dump-27466-1533049817-351841533
>         Content-Type: text/xml
>         IMAP-Dump-Version: 0
>
>         <imapdump uniqueid="710a47ca47ebc676">
>            <mailbox-url>imap://newmail.example.com/user.onlight
>         <http://newmail.example.com/user.onlight></mailbox-url>
>            <incremental-uid>0</incremental-uid>
>            <nextuid>15</nextuid>
>
>         *<uidlist>6 7 9 10 11 12 13 14 </uidlist>*
>
>            <flags>
>         ...
>
>     Note that the <uidlist> doesn't list those low number UIDs which
>     were listed in the reconstruct sequence.  In other words, I think
>     this all is harmless, but I'm not sure how much overhead it brings
>     to the whole process.
>
>     One of the servers has a total of 70GB of mail, so a complete
>     reconstruct run only takes a short while.  The other, however, has
>     over 8TB scattered over >30 partitions.  If I could avoid running
>     reconstruct across that whole wad, it'd be great.
>
>     Thoughts please?
>         -nic
>
>     -- 
>     Nic Bernsteinnic at onlight.com <mailto:nic at onlight.com>
>     Onlight, Inc.www.onlight.com <http://www.onlight.com>
>     6525 W Bluemound Road, Suite 24           v. 414.272.4477
>     Milwaukee, Wisconsin  53213-4073
>
>     ----
>     Cyrus Home Page: http://www.cyrusimap.org/
>     List Archives/Info: http://lists.andrew.cmu.edu/pipermail/info-cyrus/
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>

-- 
Nic Bernstein                             nic at onlight.com
Onlight, Inc.                             www.onlight.com
6525 W Bluemound Road, Suite 24           v. 414.272.4477
Milwaukee, Wisconsin  53213-4073

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