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Re: [Moosefs-users] Question about MooseFS metadatadistribution/recovery
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From: Steve <st...@bo...> - 2011-12-14 13:08:36
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Hi, Does anyone have a backup methology and script to take the meatlogger data off the mfs system perhaps with several generations -------Original Message------- From: Michał Borychowski Date: 14/12/2011 08:39:11 To: 'René Pfeiffer' Cc: moo...@li... Subject: Re: [Moosefs-users] Question about MooseFS metadatadistribution/recovery Hi! This is still too little information about how we could help you... What about metaloggers? Don't you have metadata_ml.mfs.back and changelog_ml.* mfs files? You could put them on FTP as tar.gz and give us a link so that we try to recover them. In "emergency" situations MooseFS tries to write metadata file on the master machine in these locations: /metadata.mfs.emergency /tmp/metadata.mfs.emergency /var/metadata.mfs.emergency /usr/metadata.mfs.emergency /usr/share/metadata.mfs.emergency /usr/local/metadata.mfs.emergency /usr/local/var/metadata.mfs.emergency /usr/local/share/metadata.mfs.emergency You can try to find them there, but as RAID went broken it is possible you won't see them. And it is impossible to recover metadata from the chunks themselves. But file data are in the chunks so if you need to find something specific it would be possible. Each chunk has 5kb header (plain text) so simple 'grep' would be enough to find what you are looking at. BTW. How much data was kept on this MooseFS installation? Kind regards Michał Borychowski MooseFS Support Manager _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Gemius S.A. ul. Wołoska 7, 02-672 Warszawa Budynek MARS, klatka D Tel.: +4822 874-41-00 Fax : +4822 874-41-01 -----Original Message----- From: René Pfeiffer [mailto:ly...@lu...] Sent: Tuesday, December 13, 2011 2:17 PM To: moo...@li... Subject: Re: [Moosefs-users] Question about MooseFS metadata distribution/recovery On Dec 12, 2011 at 1554 -0800, wkmail appeared and said: > On 12/12/2011 3:36 PM, René Pfeiffer wrote: > > … > > The biggest problem is that we cannot figure out what the RAID > > controller exactly did to the file system of the master server, and > > we haven't found any traces of a more recent metadata file. The > > metalogger system had no problem, but can it be that the metalogger > > was/is out of sync due to the silent file system corruption on the master system? > > That is a question for the devs, but early in our MFS testing with > essentially throwaway kit, we had a master fail with a broken raid. In > that case the underlying disk system had been essentially readonly for > a few days and no recent data was in /usr/local/var/mfs. > > However, the metalogger DID have accurate information and we simply > recovered using that data using the restore process and then copying > over metadata file to the now fixed master. Except for the 'on the fly > files' lost when the damm thing crashed, no other data was lost, > including files that had been received and written to chunkserver > during the time the disk subsystem was out of order. > > So my guess is that the metaloggers get their info from the masters > memory, not from a file on the master. Ok, this might be the reason then, because the master went down hard two times (first time 21 October, second time 9 December) because the RAID controller totally locked the system. I assume this could explain some missing metadata. > But that is something that should be confirmed by the devs. Thanks, René. -- )\._.,--....,'``. FL Let GNU/Linux work for you while you take a nap. /, _.. \ _\ (`._ ,. R. Pfeiffer <lynx at luchs.at> + http://web.luchs.at/ `._.-(,_..'--(,_..'`-.;.' - System administration + Consulting + Teaching - Got mail delivery problems? http://web.luchs.at/information/blockedmail.php ----------------------------------------------------------------------------- Cloud Computing - Latest Buzzword or a Glimpse of the Future? This paper surveys cloud computing today: What are the benefits? Why are businesses embracing it? What are its payoffs and pitfalls? http://www.accelacomm.com/jaw/sdnl/114/51425149/ _______________________________________________ moosefs-users mailing list moo...@li... https://lists.sourceforge.net/lists/listinfo/moosefs-users |
