- Roundtable - muug.ca

ZFS I/O strangeness
by Adam Thompson 02 Apr '12

02 Apr '12

I have a ZFS RAIDZ3 filesystem under OpenSolaris (actually a Nexenta build so a GNU userland on top of OpenSolaris kernel). "dd if=filename of=/dev/null bs=8k" gives me ~66Mbytes/sec. "cat filename | dd of=/dev/null bs=8k" gives me ~142Mbytes/sec. WTF? Why would using cat *increase* the overall speed? The only thing I can think of is readahead, but why would cat cause that to happen while dd doesn't? -Adam Thompson athompso(a)athompso.net

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Re: [RndTbl] NFSv4 locking problem
by Adam Thompson 30 Mar '12

30 Mar '12

Dunno. I've actually gone back to v3 everywhere I use nfs because v4 just seems too hard to make work properly with Linux. -Adam Trevor Cordes <trevor(a)tecnopolis.ca> wrote: >A recent update (kernel, or something else) seems to have messed up file >locking over NFSv4 on my system (yes, v4 allows for locking). > >I use locking in perl scripts over NFS and it's always worked until now. >I checked and lockd is running on the server still. > >A test case is at the bottom of this email. The problem hits on line 13 >where the open-for-write happens. It dies with "Input/output error". > >The client's /v/l/messages says: >[156474.509107] nfs4_reclaim_open_state: Lock reclaim failed! > >If I run this on a local file, not over NFS, it works fine. > >I'm using the lock functions as the sample code in the perl docs >instructs. My goal is to lock a file, read it, do things, and write it >out, all atomically. Mostly I want to protect against another instance of >the same program doing the same thing at the same time and screwing up the >file. > >My NFS server is a an older linux (Fedora 14) than the client (Fedora 16), >but the NFSv4 spec hasn't really changed in that span. > >#!/usr/bin/perl -w ># >use Fcntl ':flock'; > >$file='/data/Tmp/locktest'; > >open(LOCK,$file) or die; >flock(LOCK,LOCK_EX); > >open(IN,$file) or die; ># read from file >close(IN); > >open(ORI,">$file") or die $!; # dies here!!!!!!!!!!!!1 ># write to file >close(ORI); > >flock(LOCK,LOCK_UN); >_______________________________________________ >Roundtable mailing list >Roundtable(a)muug.mb.ca >http://www.muug.mb.ca/mailman/listinfo/roundtable >

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NFSv4 locking problem
by Trevor Cordes 30 Mar '12

30 Mar '12

A recent update (kernel, or something else) seems to have messed up file locking over NFSv4 on my system (yes, v4 allows for locking). I use locking in perl scripts over NFS and it's always worked until now. I checked and lockd is running on the server still. A test case is at the bottom of this email. The problem hits on line 13 where the open-for-write happens. It dies with "Input/output error". The client's /v/l/messages says: [156474.509107] nfs4_reclaim_open_state: Lock reclaim failed! If I run this on a local file, not over NFS, it works fine. I'm using the lock functions as the sample code in the perl docs instructs. My goal is to lock a file, read it, do things, and write it out, all atomically. Mostly I want to protect against another instance of the same program doing the same thing at the same time and screwing up the file. My NFS server is a an older linux (Fedora 14) than the client (Fedora 16), but the NFSv4 spec hasn't really changed in that span. #!/usr/bin/perl -w # use Fcntl ':flock'; $file='/data/Tmp/locktest'; open(LOCK,$file) or die; flock(LOCK,LOCK_EX); open(IN,$file) or die; # read from file close(IN); open(ORI,">$file") or die $!; # dies here!!!!!!!!!!!!1 # write to file close(ORI); flock(LOCK,LOCK_UN);

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UG News - Register Today: Unraveling the Mobile Web, Mobile Omnivore, jQuery Mobile API In-Depth, and More
by Gilbert E. Detillieux 26 Mar '12

26 Mar '12

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UG News: Save 50% on Netduino, Arduino, and Robotics Titles. One Week Only
by Gilbert E. Detillieux 22 Mar '12

22 Mar '12

FYI... ------------------------------ View in browser <http://post.oreilly.com/rd/9z1z3fjhfvb9fo5p05m2ss873mlvhu95buvej27u98g>. *Forward this announcement to your user group or a friend* <http://post.oreilly.com/f2f/9z1zfhdlo0qbg50pp79l2mi419jr2r7g7oq6lffibhg> Ebook Deal of the Week Build. Remix. Have Fun. Save 50% on Ebooks and Videos - One Week Only From making LEDs that blink to making robots that see and talk, *O'Reilly's Netduino, Arduino, and robotics titles* will propel you into the exciting world of creative electronics. This week only, save 50% on these popular ebooks and videos. Whether you're an electronics expert or novice, your adventure starts here. This deal expires Mar. 30, 2012 at 2:00am PT, and cannot be combined with other offers. Ebooks from oreilly.com are *DRM-free.* You get *free lifetime access, multiple file formats, free updates.* New Edition! Getting Started with Netduino <http://post.oreilly.com/rd/9z1zrss0u9ougi8h9ds32l5kclni828dimjb9fu9muo> *Getting Started with Netduino* <http://post.oreilly.com/rd/9z1zmh3kcgo2td36cmi9rgun5q7mv3nnp0c9552of20> By Chris Walker Released: February 2012 Was: $15.99 *Now:* $7.99 Learn More <http://post.oreilly.com/rd/9z1z0athfj69ce4lqpenpugqtrjnmqjg4dr1g8a57d8> Start building electronics projects with Netduino, the popular open source hardware platform that's captured the imagination of makers and hobbyists worldwide. This easy-to-follow book provides the step-by-step guidance you need to experiment with Netduino and the .NET Micro Framework. *Save 50% on related titles:* Making Things See <http://post.oreilly.com/rd/9z1zfaja9624o541dol4flkm3a660h9jhdpfnepjmi0> *Making Things See <http://post.oreilly.com/rd/9z1z4tbtqiir9tqc7qtb7p2vi7vsbehpf65f5vhjaj0>* Was: $31.99 *Now: $15.99 (Save 50%) * Learn More <http://post.oreilly.com/rd/9z1z329a7bckluuuolbu4leceo86n6d84rt9top1fs0> Mining the Social Web <http://post.oreilly.com/rd/9z1zusivv7cvv3ojbpr9orn3fiaktnkb315vkjjee8g> *Making Things Talk, 2nd Edition <http://post.oreilly.com/rd/9z1zlg46ur3e65o3ek6tda1ujqk8lhinothm3erk2qo>* Was: $27.99 *Now: $13.99 (Save 50%) * Learn More <http://post.oreilly.com/rd/9z1zckni0j52tepdrg4lr8tsebtkvi32ckhdh2cuaq8> Getting Started with Arduino, 2nd Edition <http://post.oreilly.com/rd/9z1zfmu81gkut1jg9ms35cphjb63k2ldiprimvuvt6o> *Getting Started with Arduino, 2nd Edition <http://post.oreilly.com/rd/9z1zn92es30e9o3ih415oph78lpn98ath2cg4jedjh8>* Was: $9.99 *Now: $4.99 (Save 50%) * Learn More <http://post.oreilly.com/rd/9z1zc12i76g5q4k98mbgt89km4sliv32qhgh2uttir8> Friends with Benefits <http://post.oreilly.com/rd/9z1zmughapd9uaaq6r34sto78mljeos0vrbh0m72m50> *Arduino Cookbook, 2nd Edition <http://post.oreilly.com/rd/9z1zr082h79pq1lqil0g24o2ejr9npjcae3m08o13rg>* Was: $35.95 *Now: $17.99 (Save 50%) * Learn More <http://post.oreilly.com/rd/9z1z0seiqbl81olbg5o6216saabs8tf98f3qhgklv40> Processing and Arduino in Tandem <http://post.oreilly.com/rd/9z1zds6iki6hvoa1htaguspc4c2iua9hsg1j86lf888> *Processing and Arduino in Tandem <http://post.oreilly.com/rd/9z1zrruigrdf7gq4jgf8fhlm1d2l4uo916vqkp11nfo>* Was: $89.00 *Now: $44.49 (Save 50%) * Learn More <http://post.oreilly.com/rd/9z1z9gq0qi8kjdeclpuhtpevtbot6dj5r56snghamu0> *View more related titles in this deal >* <http://post.oreilly.com/rd/9z1z0cre377gks3io8mk7comde7fdf9dred1583b0i0> oreilly.com <http://post.oreilly.com/rd/9z1z24hjtseu9e2r50kjcio2k8orke3urv6ab48v8v8> You are receiving this email because you are a User Group contasct with O'Reilly Media. Forward this announcement <http://post.oreilly.com/f2f/9z1zfhdlo0qbg50pp79l2mi419jr2r7g7oq6lffibhg>. If you would like to stop receiving these newsletters or announcements from O'Reilly, send an email to *usergroups(a)oreilly.com* <mailto:usergroups@oreilly.com>. O'Reilly Media, Inc. 1005 Gravenstein Highway North, Sebastopol, CA 95472 (707) 827-7000

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Skullspace Hackathon this Saturday
by Colin Stanners 16 Mar '12

16 Mar '12

Hi MUUG, For any of you that didn't know, Skullspace is having its monthly hackathon this Saturday - we have a number of interesting speakers lined up, and members will be working on fun projects. More info is at http://www.skullspace.ca/wiki/index.php/Hackathon_march2012 . Thanks, -C

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Fun facts about Amazon EC2
by Kevin McGregor 14 Mar '12

14 Mar '12

Following on last night's presentation: How many blades does Amazon have? How many racks? http://huanliu.wordpress.com/2012/03/13/amazon-data-center-size/

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UG News: Last Chance to Register - Webbots & Spiders, Mobile Interface Design, PHP & Couchbase, and More
by Gilbert E. Detillieux 12 Mar '12

12 Mar '12

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MUUG Meeting, Mar 13, 7:30pm -- The Cloud
by gedetil＠cs.umanitoba.ca 06 Mar '12

06 Mar '12

The Manitoba UNIX User Group (MUUG) will be holding its next monthly meeting on Tuesday, March 13. The meeting topic for this month is as follows: The Cloud: The catchphrase of the last year, and two years to come. The basics. Everyone by now has heard of "The Cloud." Most people, even in the IT industry, are baffled as to what the cloud actually is. This no-frills, down-to-earth presentation by Rob Keizer will be on what it is, what its uses are, and the basics of setting up a private one. March's RTFM will feature the sort(1) and uniq(1) commands, presented by Brad Vokey. The group holds its general meetings at 7:30pm on the second Tuesday of every month from September to June. (There are no meetings in July and August.) Meetings are open to the general public; you don't have to be a MUUG member to attend. ********************************************************************** Please note our meeting location: The IBM offices, at 400 Ellice Ave. (between Edmonton and Kennedy). When you arrive, you will have to sign in at the reception desk, and then wait for someone to take you (in groups) to the meeting room. Please try to arrive by about 7:15pm, so the meeting can start promptly at 7:30pm. Don't be late, or you may not get in. (But don't come too early either, since security may not be there to let you in before 7:15 or so.) Non-members may be required to show photo ID at the security desk. Limited parking is available for free on the street, either on Ellice Ave. or on some of the intersecting streets. Indoor parking is also available nearby, at Portage Place, for $5.00 for the evening. Bicycle parking is available in a bike rack under video surveillance located behind the building on Webb Place. ********************************************************************** For more information about MUUG, and its monthly meetings, check out their Web server: http://www.muug.mb.ca/ Help us promote this month's meeting, by putting this poster up on your workplace bulletin board or other suitable public message board: http://www.muug.mb.ca/meetings/MUUGmeeting.pdf -- Gilbert E. Detillieux E-mail: <gedetil(a)muug.mb.ca> Manitoba UNIX User Group Web: http://www.muug.mb.ca/ PO Box 130 St-Boniface Phone: (204)474-8161 Winnipeg MB CANADA R2H 3B4 Fax: (204)474-7609

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UG News: Last Chance - JQuery Mobile, Meaningful SEO Metrics, and More
by Gilbert E. Detillieux 05 Mar '12

05 Mar '12

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