Date: Mon, 1 Jun 2015 09:02:12 +0000 From: =?utf-8?B?S2FybGkgU2rDtmJlcmc=?= <karli.sjoberg@slu.se> To: Andreas Nilsson <andrnils@gmail.com> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: [Fwd: Strange networking behaviour in storage server] Message-ID: <1433149349.14998.181.camel@data-b104.adm.slu.se> In-Reply-To: <CAPS9%2BSturmr32jN3d1sfCsQUnyFneSMofT%2BajwqCP=LPg_nseA@mail.gmail.com> References: <1433146506.14998.177.camel@data-b104.adm.slu.se> <CAPS9%2BSturmr32jN3d1sfCsQUnyFneSMofT%2BajwqCP=LPg_nseA@mail.gmail.com>
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mån 2015-06-01 klockan 10:33 +0200 skrev Andreas Nilsson: > > > On Mon, Jun 1, 2015 at 10:14 AM, Karli Sjöberg <karli.sjoberg@slu.se> > wrote: > -------- Vidarebefordrat meddelande -------- > > Från: Karli Sjöberg <karli.sjoberg@slu.se> > > Till: freebsd-fs@freebsd.org <freebsd-fs@freebsd.org> > > Ämne: Strange networking behaviour in storage server > > Datum: Mon, 1 Jun 2015 07:49:56 +0000 > > > > Hey! > > > > So we have this ZFS storage server upgraded from 9.3-RELEASE > to > > 10.1-STABLE to overcome not being able to 1) use SSD drives > as > > L2ARC[1] > > and 2) not being able to hotswap SATA drives[2]. > > > > After the upgrade we´ve noticed a very odd networking > behaviour, it > > sends/receives full speed for a while, then there is a > couple of > > minutes > > of complete silence where even terminal commands like an > "ls" just > > waits > > until they are executed and then it starts sending full > speed again. I > > ´ve linked to a screenshot showing this send and pause > behaviour. The > > blue line is the total, green is SMB and turquoise is NFS > over jumbo > > frames. It behaves this way regardless of the protocol. > > > > http://oi62.tinypic.com/33xvjb6.jpg > > > > The problem is that these pauses can sometimes be so long > that > > connections drop. Like someone is copying files over SMB or > iSCSI and > > suddenly they get an error message saying that the transfer > failed and > > they have to start over with the file(s). That´s horrible! > > > > So far NFS has proven to be the most resillient, it´s stupid > simple > > nature just waits and resumes transfer when pause is over. > Kudus for > > that. > > > > The server is driven by a Supermicro X9SRL-F, a Xeon 1620v2 > and 64GB > > ECC > > RAM. The hardware has been ruled out, we happened to have a > identical > > MB > > and CPU lying around and that didn´t improve things. We have > also > > installed a Intel PRO 100/1000 Quad-port ethernet adapter to > test if > > that would change things, but it hasn´t, it still behaves > this way. > > > > The two built-in NIC's are Intel 82574L and the Quad-port > NIC's are > > Intel 82571EB, so both em(4) driven. I happen to know that > the em > > driver > > has updated between 9.3 and 10.1. Perhaps that is to blame, > but I have > > no idea. > > > > Is there anyone that can make sense of this? > > > > [1]: > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=197164 > > > > [2]: > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=191348 > > > > /K > > > > > > > Another observation I´ve made is that during these pauses, the > entire > system is put on hold, even ZFS scrub stops and then resumes > after a > while. Looking in top, the system is completly idle. > > Normally during scrub, the kernel eats 20-30% CPU, but during > a pause, > even the [kernel] goes down to 0.00%. Makes me think the > networking has > nothing to do with it. > > What´s then to blame? ZFS? > > /K > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to > "freebsd-fs-unsubscribe@freebsd.org" > > > Hello, > > > does this happen when clients are only reading from server? Yes it happens when clients are only reading from the server. > Otherwise I would suspect that it could be caused by ZFS writing out a > large chunck of data sitting in its caches, and until that is complete > I/O is stalled. That´s what so strange, we have three more systems set up about the same size and none of others are acting this way. The only thing I can think of that differs that we haven´t tested ruling out yet is ctld, the other systems are still running istgt as their iSCSI daemon. /K > > > Have you tried what is suggested in > https://wiki.freebsd.org/ZFSTuningGuide ? In particular setting > vfs.zfs.write_limit_override to something appropriate for your site. > The timeout seems to be defaulting to 5 now. > > > Best regards > > Andreas > > >home | help
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