November 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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Fan Control on Linux
by Giles Orr 16 Jan '18

16 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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cheap 3d printer?
by D. Hugh Redelmeier 27 Nov '17

27 Nov '17

Here's a thread about the printer I bought. We haven't used it yet so I cannot say how good it is. <https://forums.redflagdeals.com/amazon-ca-monoprice-select-mini-3d-printer-…>

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Raspberry Pi 3 Model B for $50 at Newegg.ca
by William Park 23 Nov '17

23 Nov '17

While shopping at Newegg.ca, I found <https://www.newegg.ca/Product/Product.aspx?Item=N82E16813300007&cm_sp=Homep…> -- William Park <opengeometry(a)yahoo.ca>

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For those familiar with RFC 1149 ;-)
by James Knott 23 Nov '17

23 Nov '17

https://www.arcamax.com/thefunnies/wizardofid/ https://tools.ietf.org/html/rfc1149

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HAF XB EVO case video details
by Russell 23 Nov '17

23 Nov '17

My earlier reply to William was short of the mark. The planar backplate is 1/2 way up the unit. I didn't even know it was removable. I this case it because it fits nicely where I want to put it. Here's a better description with views. https://youtu.be/6hMg4OWFWX8 -- Russell

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File larger than partition? (Docker-related)
by Giles Orr 22 Nov '17

22 Nov '17

I ran a backup today and noticed one file because it took so long to back up. I'm using FC25 on this machine, and used the OS packages of Docker. I seem to have a 100G file on a 12G partition: root@toshi7:/var/lib/docker/devicemapper/devicemapper# ls -lh total 34M -rw------- 1 root root 100G Oct 25 22:02 data -rw------- 1 root root 2.0G Oct 25 22:02 metadata root@toshi7:/var/lib/docker/devicemapper/devicemapper# df -h Filesystem Size Used Avail Use% Mounted on ... /dev/sda8 16G 12G 3.8G 75% / tmpfs 7.8G 776M 7.1G 10% /tmp /dev/mapper/home_crypt 237G 211G 24G 91% /home ... /var/ is part of / , not a separate partition. The file appears to be a plain file, not a link or device. How exactly did my backup process (rsync to an external hard drive) manage to back up 100G of data from a 12G partition? "docker info" contains some very interesting output: I've included that below. The most obvious/naive solution would simply be to exclude /var/lib/docker/devicemapper/devicemapper/ from my backups. Because I'm guessing I don't need a backup of the "Data loop file?" Is that correct? To my surprise, the file and its backup share an md5sum value - but then, I haven't touched docker in the intervening time. But I'd still really like to know either where it's storing 100G of data, or what's going on if it's not actually storing that much. It's very weird, and makes it awfully hard to calculate how big your backup will be when your partitions are evidently behaving like Tardises. Containers: 0 Running: 0 Paused: 0 Stopped: 0 Images: 8 Server Version: 1.12.6 Storage Driver: devicemapper Pool Name: docker-8:8-802519-pool Pool Blocksize: 65.54 kB Base Device Size: 10.74 GB Backing Filesystem: xfs Data file: /dev/loop0 Metadata file: /dev/loop1 Data Space Used: 27.79 MB Data Space Total: 107.4 GB Data Space Available: 4.943 GB Metadata Space Used: 618.5 kB Metadata Space Total: 2.147 GB Metadata Space Available: 2.147 GB Thin Pool Minimum Free Space: 10.74 GB Udev Sync Supported: true Deferred Removal Enabled: false Deferred Deletion Enabled: false Deferred Deleted Device Count: 0 Data loop file: /var/lib/docker/devicemapper/devicemapper/data WARNING: Usage of loopback devices is strongly discouraged for production use. Use `--storage-opt dm.thinpooldev` to specify a custom block storage device. Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata Library Version: 1.02.136 (2016-11-05) Logging Driver: journald Cgroup Driver: systemd Plugins: Volume: local Network: null host bridge overlay Swarm: inactive Runtimes: oci runc Default Runtime: oci Security Options: seccomp Kernel Version: 4.12.11-200.fc25.x86_64 Operating System: Fedora 25 (Twenty Five) OSType: linux Architecture: x86_64 Number of Docker Hooks: 2 CPUs: 8 Total Memory: 15.56 GiB Name: toshi7 ID: TJAV:PKWI:UYK2:UGAQ:GHUP:2HDO:4RBD:U54O:X7DM:SUPY:WQAM:IFTX Docker Root Dir: /var/lib/docker Debug Mode (client): false Debug Mode (server): false Registry: https://index.docker.io/v1/ Insecure Registries: 127.0.0.0/8 Registries: docker.io (secure) -- Giles https://www.gilesorr.com/ gilesorr(a)gmail.com

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Repair recommendation?
by Peter King 18 Nov '17

18 Nov '17

I woke up this morning to the beeping of my UPS informing me that my desktop computer had blown a fuse. Which it keeps doing. Right now I'm hoping it's the power supply (though there doesn't seem to be that distinctive smell in the air), but I don't have time to fix it myself. It was built for me at Filtech, which no longer exists, unfortunately. Anyone have any suggestions for an honest and reliable repair shop? -- Peter King peter.king(a)utoronto.ca Department of Philosophy 170 St. George Street #521 The University of Toronto (416)-978-3311 ofc Toronto, ON M5R 2M8 CANADA http://individual.utoronto.ca/pking/ ========================================================================= GPG keyID 0x7587EC42 (2B14 A355 46BC 2A16 D0BC 36F5 1FE6 D32A 7587 EC42) gpg --keyserver pgp.mit.edu --recv-keys 7587EC42

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