Roundtable June 2016

roundtable@muug.ca

8 participants
6 discussions

IBM "clicky" keyboards
by Adam Thompson 13 Oct '16

13 Oct '16

Enough people have wondered/asked/complained to me about this that I'm posting this now as a public service. IBM Model "M" keyboards are still available, *NEW*, today. They are expensive, but they are the original design that you can use as a melee weapon. The catch is that they don't say "IBM" or even "Lexmark" on them. They are available for purchase from the manufacturer, Unicomp, who can be found online at http://www.pckeyboard.com/. You can also find some vintage NIB units from time to time at http://www.clickykeyboards.com/. There are also a number of other manufacturers now making similar, but not quite as good, keyboards. - CVT Inc., the maker of the Avant Stellar (I own two of them), which is the direct descendant of the Northgate Omnikey, seems to have restructured and no trace of their keyboard manufacturing operation can be found online. However, Northgate keyboards are still available new-in-box from (this is a horrible site, beware) http://www.northgate-keyboard-repair.com/. - The Happy Hacking keyboard (now owned by Fujitsu, apparently) is equally comforting to some people despite having a totally different feel. They, and many others, can be had from http://www.elitekeyboards.com/ - Das Keyboard - Anything using Cherry MX Green, Blue, or White keyswitches. The "green" switches apparently are the closest anyone's come yet to emulating the IBM/Lexmark/Unicomp switches... and they can be had in MUCH cheaper keyboards, like the Rosewill RK-9000 (http://www.newegg.ca/Product/Product.aspx?Item=N82E16823201040 and http://techreport.com/review/23405/rosewill-rk-9000-series-mechanical-ke yboards-reviewed). - And there are an increasing number (yes, again, after the big die-off ca. 2009) of speciality manufacturers of "ergonomic" keyboards that are making clicky keyswitches available as an option. One of the better ones is a tiny shop in Ontario, but I can't find the name right now. References: http://en.wikipedia.org/wiki/Model_M_keyboard http://en.wikipedia.org/wiki/Unicomp http://deskthority.net/wiki/Cherry_MX -Adam Thompson athompso(a)athompso.net

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Trevor's wacky slow 10MB/s disk I/O update
by Trevor Cordes 23 Jun '16

23 Jun '16

Thanks a ton for all the great suggestions at the meeting the other night about my slow disk I/O. (For those not at the meeting, this is the slow I/O issue I've been battling with for months and have asked about here on the mailing list numerous times.) I think Adam(?) suggested testing dd with an option to avoid the cache completely, after others thought it sounded like a cache issue. The option for that (after a quick RTFM) is oflag=direct. Here's the results of that on the system after being up a day (without my hourly test running): spinning rust: 5:15am ~#dd if=/dev/zero of=/dev/sda2 bs=1M count=200 conv=fdatasync 209715200 bytes (210 MB) copied, 9.07724 s, 23.1 MB/s 5:15am ~#dd if=/dev/zero of=/dev/sda2 bs=1M count=200 conv=fdatasync oflag=direct 209715200 bytes (210 MB) copied, 2.04618 s, 102 MB/s ssd: 5:18am ~#dd if=/dev/zero of=/dev/sdb2 bs=1M count=200 conv=fdatasync 209715200 bytes (210 MB) copied, 3.38177 s, 62.0 MB/s 5:16am ~#dd if=/dev/zero of=/dev/sdb2 bs=1M count=200 conv=fdatasync oflag=direct 209715200 bytes (210 MB) copied, 0.508799 s, 412 MB/s Whoa! Indeed we have a cache issue. Disks are near full speed when writing direct to disk, but slow when going through the cache. FYI, here's what top looks like after I ran the tests (for mem info): top - 05:21:49 up 1 day, 4:43, 1 user, load average: 0.00, 0.03, 0.07 Tasks: 212 total, 1 running, 211 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.0 us, 0.0 sy, 0.0 ni, 99.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 16522952 total, 4668792 free, 706636 used, 11147524 buff/cache KiB Swap: 0 total, 0 free, 0 used. 15709432 avail Mem So it looks like buff/cache is getting quite large after all (11GB). So we'll try the next suggestion: 5:23am ~#sync ; echo 1 >> /proc/sys/vm/drop_caches top KiB Mem : 16522952 total, 15508640 free, 706136 used, 308176 buff/cache 5:24am ~#dd if=/dev/zero of=/dev/sdb2 bs=1M count=200 conv=fdatasync 209715200 bytes (210 MB) copied, 4.39049 s, 47.8 MB/s So that doesn't help at all (that's the ssd and should be 400-500MB/s). Very strange indeed! At least I have some better search terms to google with in the next few days... maybe I'll get lucky.

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muug.ca/mirror debian jessie issue
by Theodore Baschak 13 Jun '16

13 Jun '16

Good Morning: I got the following cron-apt error in my email overnight: CRON-APT RUN [/etc/cron-apt/config]: Mon Jun 13 04:00:01 CDT 2016 CRON-APT SLEEP: 3104, Mon Jun 13 04:51:45 CDT 2016 CRON-APT ACTION: 0-update CRON-APT LINE: /usr/bin/apt-get -o quiet=1 update -o quiet=2 E: Release file for http://muug.ca/mirror/debian/dists/jessie-updates/InRelease is expired (invalid since 12h 34min 34s). Updates for this repository will not be applied. I ran apt-get update again and its coming up with the same file being expired since 15 hours ago. I'll try again later this morning too, perhaps its just in the middle of pulling a new mirrored file down or something. Theodore Baschak - AS395089 - Hextet Systems https://ciscodude.net/ - https://hextet.systems/ https://theodorebaschak.com/ - http://mbix.ca/

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very strange DNS errors
by Trevor Cordes 12 Jun '16

12 Jun '16

Some recurring email bounces have tipped me off to a really strange DNS issue on the boxes I admin. I really need help on this as it's impacting a real customer in a real way: delayed emails. Often, and somewhat randomly, DNS will fail to resolve a domain. Sometimes it will fail to resolve it for >4 hours and trigger a diagnostic bounce from my sendmail. When I run tests at the command line (dig) on the domains in question (the ones I've seen in email bounces) I will often very quickly get a resolve failure, but usually 5s later another dig to the same domain will resolve 100% ok! Every box I am testing on has a similar config with BIND named 9.10 (9.8 on one box) running as the local recursive resolver. /etc/resolv.conf on all is 127.0.0.1. So that means every lookup that isn't cached is going to the root NS's. When it fails to resolve, named.log logs an entry like: 20-Apr-2016 00:37:28.276 query-errors: debug 1: client 127.0.0.1#33971 (artscouncil.mb.ca): query failed (SERVFAIL) for artscouncil.mb.ca/IN/A at query.c:7769 20-Apr-2016 00:37:28.276 query-errors: debug 2: fetch completed at resolver.c:3658 for artscouncil.mb.ca/A in 0.215778: SERVFAIL/success [domain:artscouncil.mb.ca,referral:1,restart:3,qrysent:2,timeout:0,lame:0,neterr:2,badresp:0,adberr:0,findfail:0,valfail:0] For manual tests it only logs one, for the real-life sendmail problem ones, I'll see dozen/hundreds of the same thing trying hour after hour (usually around the sendmail queue retry times). One of my boxes is *extremely* well connected in the US, and while it seems to have errors slightly less often, it still has them. All the rest are on various levels of Shaw or MTS, res or business. This seems to have just started popping up maybe 6 months ago. It feels like it's getting worse. I've setup an easy test, on the actual domains with the most problems: rndc flush dig +short sportmanitoba.ca dig +short gymcan.org dig +short brandoneagles.ca dig +short interactivegym.org dig +short artscouncil.mb.ca rndc flush dig +trace sportmanitoba.ca dig +trace gymcan.org dig +trace brandoneagles.ca dig +trace interactivegym.org dig +trace artscouncil.mb.ca Maybe some others can run those tests on their boxes (but only if you're running BIND as caching resolver, which many/most people won't be). Here's where it gets interesting the +short tests I can get to fail at least 1 of the domains (at random) about 1/8 of the time! On at least 5 different boxes out there! But +trace has never failed once on any box or any domain. It's like +trace does something different, maybe slowing the process down or something, that allows it to always succeed. (Failure for the +short is a missing line in output, +trace you have to look at the domain/ip returned near the bottom.) So, is it just these particular domains?? Something wrong on their (DNS) side? Or is it more domains, not just these? Is there any way to diagnose what exactly is failing? I find it bizarre that *all* of these domains regularly go down for 4+ hours causing an email bounce!?! Or is there something horribly wrong on my BIND caching DNS servers? Perhaps they are slow, and I'm my BINDs are just not waiting long enough. Is there a way to tell BIND to be more patient waiting for DNS packets to come in? Maybe it's something regarding IPv6? (I'm doing this all in IPv4 and have no current interest in 6. And I'm only looking for A records.) I have packet traces of the above sample commands when the lookups fail, but I can't really figure out what it's doing, other than one boatload of traffic for a tiny dns query. I can provide a trace privately on demand if you think you can help. Even more odd, I never seem to have a problem with interactive things like web browsing. If this was a problem with all domains, I should see this in firefox all the time, but I don't. Maybe Firefox doesn't even obey resolv.conf and does its own thing, or retries heavily itself? I also checked to ensure my iptables aren't dropping packets related to this. Lastly, answers of "just use 8.8.8.8" aren't helpful because I also need to handle dynamic local, and in some cases, external DNS (often with multiple views), all in the same BIND/box (and I like uniformity across boxes for ease of admin). Sure, I could try another resolver, but I see no reason BIND can't be made to work, as it has for me for 20 years. And if this is a BIND bug, I want to submit it to help solve it. Thanks guys!

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MUUG Meeting, June 14, 7:30pm -- Gentoo
by Gilbert Detillieux 08 Jun '16

08 Jun '16

The Manitoba UNIX User Group (MUUG) will be holding its next monthly meeting on Tuesday, June 14. The meeting topic for this month is as follows: Gentoo Eric Raine will be presenting on the Gentoo Linux Distribution. Differences in installation from Ubuntu will be covered. Also covered is how to configure installation of packages and update. Gentoo is a free operating system based on either Linux or FreeBSD that can be automatically optimized and customized for just about any application or need. RTFM: Terminal Control Commands Due to a recent influx of new and novice members, Trevor Cordes will be doing an RTFM instead of a daemon dash this month. The topic is something every *NIX user should master: terminal control commands (e.g. ^Z and ^L) and rudimentary job control. These little dual-key presses will streamline your terminal sessions and make you more efficient. You'll wonder how you ever got by without them! 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 *NEW* meeting location for this month: *Room 1M28* (1st floor) Manitoba Hall, University of Winnipeg, entrance on Ellice Ave. between Spence St. and Balmoral St. Parking is available on the surrounding streets and in the lots on nearby streets. Look for signage once you're at the building, or ask a security guard. ****************************************************************** 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 -- Manitoba UNIX User Group E-mail: <gedetil(a)muug.mb.ca> c/o Gilbert E. Detillieux Web: http://www.muug.mb.ca/ University of Manitoba Phone: (204)474-8161 Winnipeg MB CANADA R3T 2N2 Fax: (204)474-7609

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Fedora upgrading
by Kevin McGregor 03 Jun '16

03 Jun '16

Does anyone know how upgrade-able Fedora is? Say, Fedora 21 -> 22 -> 23? What about skipping a version? Does that work, or must you go through intermediate versions? Or is it best just to re-install each time? Thanks, Kevin

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Roundtable June 2016