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Re: [CentOS] C7 and docker storage
by m.roth＠5-cent.us 01 Dec '17

01 Dec '17

Gianluca Cecchi <gianluca.cecchi(a)gmail.com> wrote: > Date: Thu, 30 Nov 2017 09:55:58 +0100 > On Wed, Nov 29, 2017 at 10:23 PM, <m.roth(a)5-cent.us> wrote: > >> The latter would explain the message my user's job gave him when it tried >> to umount / >> >> A bit of googling, and I see something called overlayFS can be used... but >> I know nothing about that, or how dangerous it is. Anyone got a pointed >> to something more than the minimal how to configure docker to use it? >> > You could follow CentOS Atomic SIG > https://wiki.centos.org/SpecialInterestGroup/Atomic > http://www.projectatomic.io/download/ > > and/or read here and adapt in case for your storage needs: > http://www.projectatomic.io/docs/docker-storage-recommendation/ > > See also here for overlayfs addiction in CentOS Atomic Host in September > this year > https://seven.centos.org/2017/09/new-centos-atomic-host-with-overlayfs-stor… > Interesting, but it doesn't help me: I can't rebuild the server, it's in use, and I yum installed docker from the std. repos. What I see from the links tells me how to switch storage, not how to manually configure overlay2 storage, and whether I can do as I said, and point it to an NFS-mounted location. mark

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Re: [CentOS] Good linux software RAID primer advise
by Miguel Medalha 01 Dec '17

01 Dec '17

>> Could someone recommend good Linux software RAID primer. It would >> be good if it has good coverage of monitoring and dealing with failures. https://raid.wiki.kernel.org/index.php/Linux_Raid

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Partition advice
by Kenneth Porter 01 Dec '17

01 Dec '17

I'm setting up a new mail server (dovecot + sendmail + SpamAssassin + ClamAV + MIMEDefang) to replace an aging CentOS 6 box. The new box is a low-end PowerEdge with an SSD, 3 4TB red drives on a PERC RAID controller which I'll probably set up RAID5, and possibly mirrored internal SD cards as a boot device. I'm debating how to partition it and am soliciting advice. My initial instinct is to put /boot and the OS on the SSD and the home directories with their mail store on the RAID array. I might put a rescue partition on the internal SD drive (which is normally intended for a VM host). Does anyone see anything wrong with that? Should I do something different? Anything I should avoid putting on the SSD, such as swap, /tmp, and /var/tmp? I've been running Red Hat as a small office server since 5.2 back in the 90's. I'm trying to create a system that's easy to fix when it breaks. I find that's the real power of Linux over any other OS: It's easy to fix when it breaks. Oh, and backup will be to an external USB drive using BackupPC, with the drive regularly swapped off-site, plus an off-site rsync mirror.

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Good linux software RAID primer advise
by Valeri Galtsev 01 Dec '17

01 Dec '17

Dear Experts, Could someone recommend good Linux software RAID primer. It would be good if it has good coverage of monitoring and dealing with failures. I inherited a couple of boxes with big bunch of software RAIDs each, and I even may have some problems, but I don't want to bother anybody with specifics unless I really hit brick wall, not just my own ignorance. Thanks in advance for all your answers! Valeri ++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++

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Gnome boot problem (again :-) )
by vychytraly . 01 Dec '17

01 Dec '17

Hello friends I was using EL7 on gnome 3 for few months without any problem. Even 2 hours ago I had the computer (Laptop running on Nvidia-Prime) turned on and everything was working without flaw. But when I turned on the computer few minutes ago, I got login screen (which does not usually happen, since I have autologin turned on) and when I entered my login credentials I got black screen and went back to login screen. Everytime I entered my credentials the same thing happened so I was stuck in endless login loop. At first I thought it was caused by gnome-extension I updated to new version today. So I restarted the pc, went to runlevel 3, renamed the folder with extension in /home/user/.local/share/gnome-shell/extensions/"extension_name" to another name as a quick and dirty way to disable it. I restarted the pc and now I can't even get to login screen. I get stuck at text saying: "A start job is running for Wait for Plymouth Boot Screen to quit (25s / no limit)". I can go to another cmdline session and when I try to run exec gnome-session nothing happens, I just get logged off the cmdline session and must log in again. When I try to run startx my screen blinks and I get this output: xauth: file /home/user/serverauth.2372 does not exist. Output from command systemctl status gdm says: Starting gnome display manager Started gnome display manager GLib-GObject: g_object_set_valist: object class "GdmSession" has no property named "display-is-initial", GdmDisplay: display lasted 2.909... Seconds gdm_display_finish: assertion 'GDM_IS_DISPLAY (self)' failed journalctl -r gives me these errors: vgargb: this pci device is not a vga device gdm_display_finish: assertion 'GDM_IS_Display (self)' failed Process 1165 (gnome-shell) of user 42 killed by SIGSEGV - dumping core Process 1194 (gnome-shell) of user 42 killed by SIGSEGV - ignoring (repeated crash) Unrecoverable failure in component org.gnome.Shell.desktop Please could you help me with finding the problem? I am not really sure what could be the issue, since I did not change or update any packages today, nor changed the configuration files. Only change I am aware of was the update of the gnome-extension. Thank you very much and have a nice day O.

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Accessing KRB5 NFS from local system accounts
by Gordon Messmer 30 Nov '17

30 Nov '17

I recently noticed that spamassassin (running as the local "daemon" account) will hang some of the time when processing messages, and tracked it to the process attempting to access ~user/.spamassassin/user_prefs. I believe that should return an access failure, but sometimes the process stalls instead. In any case, I'd like to allow access, but my understanding is that processes without a Kerberos ticket cannot access an NFS4 filesystem with sec=krb5. Is that correct? If so, how would I allow a local system account to access globally readable files? Should I create a keytab, and set KRB5_KTNAME in the spamassassin environment? Does anyone working with NFS and krb5 have any tips?

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C 7, docker, and storage
by m.roth＠5-cent.us 30 Nov '17

30 Nov '17

I may have missed some overnight replies to my question from yesterday - if so, sorry. >From my googling, it looks like I should change from the loopback device to overlayFS (with overlay2). What I haven't found is, first and foremost, more clarity on configuring storage. It *appears* that the loopback storage is just a directory under /var/lib/docker (yet I see a reference in someone's blog to ~docker - *is* /var/lib/docker intended as ~docker? Can I make a docker directory elsewhere, on another filesystem that has a lot of space, and configure docker to use that, or do I need to symlink from /var/lib/docker to the new place? And should I move all the old stuff under /var/lib/docker to the new location (of course have shut down docker)? mark

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Admins supporting both RHEL and CentOS
by Joseph L. Casale 30 Nov '17

30 Nov '17

With a few exceptions, I see most admins treat CentOS as a single rolling release and rely on the ABI commitment assuming things just work between point releases. On the other hand I see the opposite with RHEL where admins constrain installations to the point release. What is the case with users on this list who support both? Thanks, Joseph L. Casale

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Failed attempts
by Jerry Geis 29 Nov '17

29 Nov '17

hi All, I happened to login to one of my servers today and saw 96000 failed login attempts. shown below is the address its coming from. I added it to my firewall to drop. Failed password for root from 123.183.209.135 port 14299 ssh2 FYI - others might be seeing it also. Jerry

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Missing /usr/share/perl5 in C7
by Mark Haney 29 Nov '17

29 Nov '17

I'm under a bit of a crunch here, so any immediate help would be appreciated. We kickstart our customer boxes and have started migrating to CentOS 7. We're running Radiator 4.6 1 (I know, but bear with me) and we just deployed our first radius box to a customer to be turned up today. (I know, I know. I had no idea it wasn't being tested sooner than this.) I was brought in because the strict.pm perl module was missing and causing compilation errors. It turns out nearly the entire /usr/share/perl5/ directory was pretty much empty. I ended up having to copy that directory over from another C7 server which was intact. yum whatprovides /usr/share/perl5/strict.pm tells me it's the base perl-5.16.x package, which is installed on this box. Any idea what happened? -- Mark Haney Network Engineer at NeoNova 919-460-3330 option 1 mark.haney(a)neonova.net www.neonova.net

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