In the meantime Bakbone support managed to send me a working (binary) patch fixing the problem and I was asked by Bakbone to post this information. So, if you experience the problem described below, please contact Bakbone support.
Best regards, Georg Altmann
--On Montag, November 22, 2004 19:33:51 +0100 Georg Altmann <[EMAIL PROTECTED]> wrote:
I have a problem running the backup software Netvault from Bakbone (http://www.bakbone.com) under FreeBSD 4.10. We are using Netvault to make backups of two servers and several workstations in our network. Backups are first staged to disk and later transferred to an ADIC FastStor 2 (LTO 1) library.
The problem occurs when the backup is transferred from disk to tape and if the backup job spans multiple tapes (not virtual media!): Netvault recognizes the end-of-media, loads a new media for the job and then hangs endlessly trying to write to the new media.
Bakbone claims, that this is a problem with SysV shared memory and semaphores in FreeBSD (and therefore not their software). Their support also sent me a patch for Netvault (unfortunately not a binary one, so I cannot test it) which is allegedly known to work around the problem. I attached it below. Note the added "#if defined(PLATFORM_FREEBSD)" bits in the code. To my understanding, the patched code polls the semaphore instead of waiting for it. Please also note, that I configured Netvault to use network sockets instead of shared mem for the transfer and the problem persists (I did this by only selecting "TCP Data Transfer" in the configure device tab for both the tape and the virtual library and by adding [Data Channels]\nForce Sockets=TRUE to configure.cfg as proposed by Bakbone support, for anyone familiar with netvault). So I assume, the problem is really only related to semaphores and not at all to shared memory(?).
I hope that someone can guess from the code if this really leads to a deadlock because of a FreeBSD bug in SysV sempaphore handling. I have already skimmed FreeBSD PRs for semaphore bugs, but no post really seemed related to this specific problem (see http://www.freebsd.org/cgi/query-pr-summary.cgi?category=&severity=&prior ity=&class=&state=&sort=none&text=semaphore&responsible=&multitext=&origi nator=&closedtoo=on&release=). So, maybe somebody is able to make clear whether I should urge Bakbone to fix their buggy software or look for a patch for the FreeBSD kernel and/or libraries.
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-------------------<>-----------------------------< Georg Altmann <> Phone +49 (0)89 17809328 < LAS-CAD GmbH <> Fax +49 (0)89 172594 < Brunhildenstr. 9 <> e-mail [EMAIL PROTECTED] < D-80639 Munich <> backup [EMAIL PROTECTED] < Germany <> http://www.las-cad.com < -------------------<>-----------------------------<
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