Date: Wed, 08 Dec 2004 17:08:55 +0100 From: Georg Altmann <galtmann@las-cad.com> To: freebsd-questions@freebsd.org Subject: Re: semaphore problem with Bakbone's Netvault on FreeBSD 4.10 Message-ID: <F54E43BFB3FF627B5DC187F3@[192.168.98.23]> In-Reply-To: <C79517C1DAEEB0C790F8D4E7@[192.168.98.23]> References: <C79517C1DAEEB0C790F8D4E7@[192.168.98.23]>
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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 <galtmann@las-cad.com> 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. [ removed ] -- >-------------------<>-----------------------------< > Georg Altmann <> Phone +49 (0)89 17809328 < > LAS-CAD GmbH <> Fax +49 (0)89 172594 < > Brunhildenstr. 9 <> e-mail galtmann@las-cad.com < > D-80639 Munich <> backup george@george-net.de < > Germany <> http://www.las-cad.com < >-------------------<>-----------------------------<
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