Date: Thu, 30 Jan 2014 22:21:41 +0000 From: Ben Laurie <ben@links.org> To: "Justin T. Gibbs" <gibbs@scsiguy.com> Cc: freebsd-scsi@freebsd.org Subject: Re: Dropped interrupts Message-ID: <CAG5KPzzrenHbYSBY5zQ1GNKg%2BT2nY0aAKp3uGSw=Rxn1=KYnow@mail.gmail.com> In-Reply-To: <888F991A-96C7-48C0-AAC6-0D432BD78A46@scsiguy.com> References: <CAG5KPzxUAnORPSyJDrSdBBNE7MBi-dD=M6=E1rMG%2Bc8rn4deUQ@mail.gmail.com> <AE41EB93-26BD-4BD0-9913-7CD0A5B6E1A4@scsiguy.com> <CAG5KPzwR5=WNKc5hck8F7CtCtk3mivwYFRFeCJT_zWdnetW=3w@mail.gmail.com> <84D23688-DDC6-421E-9D21-3DA646229038@scsiguy.com> <CAG5KPzxqxmzfnAiUyVyApMs5XqKpH0F0sbTxy1h=4cL=rEROpQ@mail.gmail.com> <CAG5KPzyPXLEOAFKTAW%2BJaai=XbT3mi5yGHs1LnUbMcD-LfQ1YQ@mail.gmail.com> <CAG5KPzzVpvH=miguqKnO0pA2jmWm-_7s7W-Nbh%2BVeHKv7x7ikw@mail.gmail.com> <8680A21D-78D7-4B65-A502-17F0C3B70291@scsiguy.com> <CAG5KPzwvBoBvh210Vn5GG6eBVNXKWCkuh6J_FLGao0L6aPAmcw@mail.gmail.com> <888F991A-96C7-48C0-AAC6-0D432BD78A46@scsiguy.com>
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On 26 January 2014 22:46, Justin T. Gibbs <gibbs@scsiguy.com> wrote: > On Jan 26, 2014, at 1:52 AM, Ben Laurie <ben@links.org> wrote: > >> On 25 January 2014 17:15, Justin T. Gibbs <gibbs@scsiguy.com> wrote: >>> On Jan 24, 2014, at 10:44 PM, Ben Laurie <ben@links.org> wrote: >>> >>>> Aha, finally got the error again... >>> >>> I don't know enough about your backup or Bacula to know if this is amou= nt that should be written, but we attempted a write in variable block mode = of 64512 bytes. >> >> I don;t think there's anything wrong with that. Not at the machine >> right now, but I think that's actually the default max block. No idea >> why. >> >>> The command, data transfer list, and controller state are all consisten= t with this. The command was successfully transferred to the tape drive, b= ut it never transitioned to data phase to allow us to begin the data transf= er. (In parallel SCSI, the target controls all state transitions). >>> >>> Since there are no parity errors or other indications of a transport er= ror, my hunch is that this is a tape drive issue. Are you running the late= st available firmware for it? >> >> No idea, its a very old LTO-2 drive. I'll see if I can find an update. >> >>> How many write cycles do you have on your media? >> >> I have seen this error on brand new media. I'd guess the most cycles >> any tape has had is around 10. >> >>> When was the last time you cleaned the drive? >> >> LTO drives are self-cleaning. So ... never. > > This is a popular misconception. LTO drives include brushes deployed dur= ing load or unload to remove large particle contamination off the head. Th= is increases the time interval between traditional cleanings, but doesn't m= ake them unnecessary. Certain LTO drives will tell you (e.g. light a LED) = when they require cleaning, but I don't know if this is one of them. There= have also been firmware bugs on some drives that prevent the cleaning indi= cator from working as expected. > > If the drive has over 500 hours on it, I would suggest a cleaning pass. Are you suggesting that a need for cleaning could cause this problem? > > -- > Justin
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