December 2017 - Talk - lists.gtalug.org

war story: power failure makes CentOS system unbootable
by D. Hugh Redelmeier 30 Sep '22

30 Sep '22

tl;dr / spoiler: change fstab so that /boot/efi is not automatically mounted. See the recommendation at the end of this message. My gateway computer is a little PC running CentOS. It does not come back after a power failure. The reason (as best I can tell) is interesting and I think that I have a fix. My system is UEFI. It boots from a UEFI system partition, known as /boot/efi to Linux. If this gets corrupted, it won't boot. It is a VFAT partition. On my gateway (a Zotac Zbox RI321, a cute little box with two ethernet ports), the UEFI firmware apparently won't boot if the dirty bit is set in the system partition. CentOS normally runs with /boot/efi mounted. So when the system isn't shut down cleanly, the dirty bit will be on. Consequence: the system is not going to boot after a power failure. Odd observation 1: if I put a live Fedora 25 USB stick in the system and try to boot in this otherwise-unbootable state, CentOS boots from the main disk. So this really looks like a firmware bug/quirk. Odd observation 2: fsck doesn't seem to automatically fix the system partition. Once CentOS 7 booted, I dismounted /boot/efi and did an fsck on it. $ sudo fsck /dev/sda1 fsck from util-linux 2.23.2 fsck.fat 3.0.20 (12 Jun 2013) 0x25: Dirty bit is set. Fs was not properly unmounted and some data may be corrupt. 1) Remove dirty bit 2) No action ? 1 Leaving filesystem unchanged. /dev/sda1: 16 files, 2420/51145 clusters Googling got me to <https://www.centos.org/forums/viewtopic.php?t=50917> In particular, this advice seemed quite good: ==== recommendation ==== Two other changes I recommend for UEFI systems, to each OS's /etc/fstab. - For the /boot/efi mountpoint, add the mount options x-systemd.automount,noauto - Change fs_passno (last column) to a 1 or 2; the canonical fstab instructions suggest 2, but systemd treats 1 and 2 as the same. The first change means the EFI System partition will not be automatically read-write mounted at boot time; it's a bad idea this is the default because it puts the ESP at risk especially if ther are crashes, FAT has no journal and will therefore always be marked dirty in such a case; no other UEFI OS mounts the ESP by default. Second, if anything tries to access /boot/efi (read or write), systemd will automatically mount it, and because of the fs_passno 1 or 2, it will fsck it first and that fixes and clears the dirty bit in case it's set. Right now without these changes, it's just a matter of having the right number and bad timing of crashes to render the EFI System partition corrupt.

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Build critique request and the story behind it.
by Russell 19 Apr '18

19 Apr '18

This year I purchased an APC UPS because of my flakey connection to the grid. Ominous read clicks coming from my boot drive cemented that decision. I am happy to say that not only did I avoid my biannual unexpected shutdowns, the UPS also sensed transient RF spikes. It begins to click, switching to the battery and back to mains, even though there is no visible disruption to service, although the emergency lighting in the hallway was triggered and beeped itself on. I decided to purchase a case and build a new desktop. I waited till now because I was loosely following Sarah Sharp, of Intel and listened to her comments on USB. Version 3.0 is RMA as of Jan this year and her general comment is that hardware development has peaked and so the immediate future is in developing software. Here is the case I chose. I take delivery tomorrow. http://www.coolermaster.com/case/lan-box-haf-series/haf-xb-evo/ Newegg has this combo on offer. Intel Core i5-7500 Kaby Lake 4-Core 3.4 GHz CPU w water cooling unit ASUS STRIX H270F GAMING MB G.SKILL 2 x 8G DDR4 As a creative anachronist or purposefull recycler, I haven't built a complete system from all new parts in a dozen years. I thought I'd get my hand in before arthritis takes over my hardware chops completely. I'd appreciate any warnings and caveats regarding this combo. I'm still window shopping but what I'm looking for is stability and longevity over gaming. This combo has DDR4 and USB 3.1. I'm kind of fixed on the usb but I'm not married to the ram. So suggestions which lower the cost are most appreciated. I have a 650w Corsair p/s which is ok but a big factor for me is the ambient noise and recommendations on a quiet supply would be appreciated. Noise is why I'm trying out water cooling. From the reviews on the case I'll probably have to replace the case fans, but who knows I might get lucky. I follow with interest the posts on UEFI, secure boot, SElinux, USB, udisks, udev, mobile linux and systemd. Now is my time to see if I have learned anything. Thanks to all posters. Regards -- Russell Sent by K-9 Mail

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Any Debian Developers here can help me sign my GPG key?
by tlugys.ats＠spamgourmet.com 26 Feb '18

26 Feb '18

Hi GTALUG members, Do we have any Debian Developers here? I am in the second step of becoming New Debian Maintainer process -- https://nm.debian.org/process/194 and now need to have my GPG key signed by a Debian member. I was directed to the THUG group (Toronto (GNU)/Hurd User Group) http://www.nongnu.org/thug/ but only to find that their listed email (thug(a)gnu.org) is no longer working. So I'm in a bad position now, and really hope that there is a Debian Developer here, or you know of, that can help me. I live in GTA, North York to be exactly. Any help can comfort my desperate heart. Thanks Antonio

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Linux Journal, RIP
by Stewart C. Russell 01 Feb '18

01 Feb '18

Looks like last month was their last month of even digital publication: https://www.linuxjournal.com/content/linux-journal-ceases-publication Jason Scott has saved everything he can on archive.org: https://archive.org/details/linuxjournalmagazine Looks like he could use some help creating tables of contents for all the issues, though: So, next bit. I took the table of contents from a page on the site to generate the table of contents here: https://archive.org/details/Linux-Journal-2011-06 - so, unfortunately, this has to be done for each issue. Any brave soul want to do this task? — @jscott : https://twitter.com/textfiles/status/938198975982850048 I'm sure it would be an amusing SMOP for someone on the list, and Jason's good people to work with. archive.org's Python interface is pretty powerful, too — https://internetarchive.readthedocs.io/en/latest/ cheers, Stewart

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Fan Control on Linux
by Giles Orr 15 Jan '18

15 Jan '18

I have a very old laptop I'm trying to rehabilitate and use with Debian: it's got an AMD Turion chip and 1G of RAM. Works fine. But one annoying problem under Linux: the fan runs flat out all the time. If the 'sensors' command is correct, the CPU has never gone above 35C, so the fan isn't running like that because of the heat. I also used this machine recently to run Darik's Boot And Nuke (aka "DBAN") on a hard drive: that's a Linux kernel, and the fan wasn't running full out. Not sure what that proves, except that the fan doesn't have to run full out under a Linux kernel. I've installed "lm_sensors," I've installed "fancontrol", I've run 'lmsensors-detect' (which is 'sensors-detect' under Fedora and Ubuntu - I've tried three Linux OSes with essentially identical results). I've run 'pwmconfig' which tells me "There are no pwm-capable sensor modules installed." I've written a file into /etc/sensors.d/fan-speed-control.conf that said this: chip "k8temp-pci-*" set fan1_div 4 (This last at the suggestion of ArchWiki, which says reducing the fan multiplier can make it accessible to Linux.) But running 'sensors -s' to reload the config is greeted with "Error: File /etc/sensors.d/fan-speed-control.conf, line 2: Unknown feature name k8temp-pci-00c3: No such subfeature known." On an off-chance I tried "fan0_div" and "fan2_div" but same answer. This has exhausted most of the mainstream remedies suggested by Google. At this point I'm stumped: can anyone else suggest ways to get a handle on this fan? -- Giles https://www.gilesorr.com/ gilesorr(a)gmail.com

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Dinner in the usual place?
by David Collier-Brown 09 Jan '18

09 Jan '18

The last few times it was Kabul Express, are we headed there tonight? --dave

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ASCII table (FYI)
by William Park 28 Dec '17

28 Dec '17

Here are 2 tables: <https://wiki.gtalug.org/user:william:start> - ASCII table -- {man ascii} is good enough for one-off lookup. But, if you need a permanent PDF table, here is something I created: {ascii.pdf}. The control character names are mostly generics, but what's included are the names used by Epson's ESCPOS interpreter. - Netmask -- I could never remember the decimal number for various netmasks. So, I created a little table: {netmask.pdf} Enjoy! -- William Park <opengeometry(a)yahoo.ca>

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"Ubuntu 17.10 Temporarily Pulled Due To A BIOS Corrupting Problem"
by D. Hugh Redelmeier 25 Dec '17

25 Dec '17

<https://www.phoronix.com/scan.php?page=news_item&px=Ubuntu-17.10-BIOS-Corru…> <https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1734147> This is scary but hard to evaluate. The best guess is that there is an oddity in the Lenovo firmware that interacts with a recent Linux kernel change in a bad way. - it is not specific to Ubuntu: it also effects some Acer, Toshiba, Dell, and other notebooks. See the list in the Launchpad report. - Maybe the problem is fixed by this or something related <https://github.com/torvalds/linux/commit/d9018976cdb6eefc62a7ba79a405f6c966…> We should let wizards work on this. If it hits you, it seems that your current setup will be very important to preserve until there is a fix. In particular, you will only be able to boot from the current boot entry, and that means your EFI partition's GUUID is important and the path to the .efi file (shim?) that gets booted is important. If you wipe your disk you may never be able to boot again. Much of this is guesswork on my part.

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personal webpage for GTALUG members?
by William Park 24 Dec '17

24 Dec '17

Hi, I have ASCII tables (PDF) that I created and used over the years, and I would like to make it available to public. Is there "user" section in the wiki, where I can create entries with file attachments? I wouldn't mind paying "premium" membership for that. I don't really feel like getting a domain for few static pages. -- William Park <opengeometry(a)yahoo.ca>

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Apache Traffic Server HA
by Greg Martyn 22 Dec '17

22 Dec '17

Has anyone run Apache Traffic Server in production? I've used it for a proof-of-concept before, and I like it overall, but I'm about to recommend its use and would like to hear any horror stories. I'm planning on using it as a reverse proxy cache for a site that is expected to have a couple tens of thousands of active users at peak. I'd have HAProxy in front for HA, with a mirror setup of everything below it, talking to ATS, with another HAProxy behind ATS for load balancing the origin servers. Any comments welcome. Thanks! Greg

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