Discuss August 2019

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82 participants
60 discussions

SSD for Centos SWAP /tmp & /var/ partition
by Keith Roberts 03 Sep '25

03 Sep '25

Has anyone actually used a SSD in a Centos setup? My little experiment with a s/h WD drive for /tmp and SWAP partitions kicked the bucket on Wednesday, when the poor WD drive caught the click-of-death. It was a s/h drive to start with and lasted about 4 months. But that was without the /var/log/ partition being written to it, as I mounted that back onto /var/log from the original drive. So I had to install another (WD) drive, and repartion it and rebuild my RPM package database, from the backed-up Packages file. That seems to be all OK now. I'm wondering if it would be a good idea to use a new SSD for moving all the disk i/o to, that Linux likes to do so often. Plus putting SWAP onto a decent SSD should speed things up somewhat. Here's a short video of a laptop fitted with a SSD drive booting macOS, compared to a similar laptop booting from the standard HDD. The laptop with the SSD boots and loads some apps in 28 seconds. The other one takes twice as long. http://eshop.macsales.com/shop/SSD/OWC/Mercury_Extreme_Pro_6G/?utm_source=t… Kind Regards, Keith Roberts ----------------------------------------------------------------- Websites: http://www.karsites.net http://www.php-debuggers.net http://www.raised-from-the-dead.org.uk All email addresses are challenge-response protected with TMDA [http://tmda.net] -----------------------------------------------------------------

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Issues booting centos7 [dracut is failing to enable centos/root, centos/swap LVs]
by Yannis Milios 01 Feb '25

01 Feb '25

Hello, I'm having a strange problem booting a new centos7 installation. Below some background on this. [I have attached the tech details at the bottom of this message] I started a new CentOS7 installation on a VM, so far all good, o/s boots fine. Then I decided to increase VM disk size (initially was 10G) to 13G. Powered off the VM, increased the vhd via the hypervisor, booted from CentOS livecd, selected "recover my centos installation". Then I used the following sequence of commands to make the new vhd size "visible" to the o/s ... - ran fdisk /dev/sda and deleted partition 2. (This is the LVM partition where the o/s is stored. The first partition is /boot [xfs] partition *non lvm*.) - created a new partition with same starting sector as before deleting it, but a different ending sector (to reflect to the increased space). - set partition type to 8e (lvm), saved settings and exit. - ran pvresize and lvresize to make new space visible to the o/s.All good, I can see the space increase on 'lvdisplay centos/root'. - ran 'mount /dev/mapper/centos-root /mnt/root' to temporarily mount the o/s partition. - ran 'xfs_growfs /mnt/root' to resize the o/s fs to the new size. It was successful and I could actually chroot to the o/s and verify new disk size. - rebooted and tried to boot from hdd this time. Grub menu shows up and loads default kernel (3.10.0-862.9.1.el7.x86_64). - after initial kernel boot up process, booting continues to initrd and then it's where the problem starts... - looks like dracut has issues locating/enabling /dev/mapper/centos-root (lv) and as a result it cannot boot to the 'real' root fs (/). - while in dracut shell, I execute the following command sequence: 1. lvm lvchange -ay /dev/centos/root 2. lvm lvchange -ay /dev/centos/swap 3. ln -s /dev/mapper/centos-root /dev/root 4. exit ...and the o/s boots fine...so looks like the pv,vg,lv is detected properly while in initrd, but somehow dracut has difficulties enabling the root,swap LVs ? - While in o/s, I rebuild initrd by using: 'dracut -f -v -a lvm' Note, I have to use '-a lvm' as for some reason, if don't, the lvm utils (lvm,lvm_scan) are not being included to the initrd, not sure why this happens. After rebooting, same thing happens, I have to manually boot the system via dracut shell. I'm a bit stuck at this point, any clues what I'm doing wrong in here ? As I previously said, this is a new installation, so I could simply reinstall the whole thing, but I would rather try to find out some answer to why is this happening ... :-) [curiosity] Some additional details: ================== I've attached /run/initramfs/rdsosreport.txt file [generated while in inird] here: https://privatebin.net/?fdc4052c0c402884#gdB/QYR3IeR55SxUbjfrkZPQfJ7jMxiUxq… o/s ver=CentOS Linux release 7.5.1804 (Core) [root@localhost ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 13G 0 disk ├─sda1 8:1 0 500M 0 part /boot └─sda2 8:2 0 12.5G 0 part ├─centos-root 253:0 0 11.5G 0 lvm / └─centos-swap 253:1 0 1G 0 lvm [SWAP] [root@localhost ~]# cat /etc/default/grub GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT="console" GRUB_CMDLINE_LINUX="rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rd.shell rhgb" GRUB_DISABLE_RECOVERY="true"

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Re: [CentOS] upg. CentOS 7.5 to 7.6: unable to mount smb shares - samba NT domain member using ldap
by Gordon Messmer 27 Jan '20

27 Jan '20

On 1/2/19 12:09 PM, Miroslav Geisselreiter wrote: > some parameters from smb.conf: > [global] > workgroup = NT4DOMAIN > netbios name = nt4member > security = domain > passdb backend = ldapsam:"ldap://ldap1server.intranet.xx > ldap://ldap2server.intranet.xx" I'm not sure it makes sense to use "security = domain" with an ldap passdb backend. If you're using a real NT4 domain, then you shouldn't need a passdb backend at all. If you're not in an NT4 domain, then you should set "security = USER". The man page for smb.conf notes "This mode will only work correctly if net(8) has been used to add this machine into a Windows NT Domain." Did you add this host to a Windows NT domain, using "net join ..."?

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CentOS 7.6 1810 vs. VirtualBox : bug with keyboard layout selection
by Nicolas Kovacs 20 Jan '20

20 Jan '20

Hi, I'm currently working on my next Linux book, which will be an elementary course about CentOS administration. I'm using VirtualBox for all the installer screenshots. Since CentOS has recently been upgraded to version 7.6, I thought I might as well base all book references on this version. So I downloaded the 7.6 1810 minimal ISO and started a fresh installation in VirtualBox. I'm using a Swiss French keyboard layout (ch-fr or fr_CH-latin1), so one of the first things I do in the installer is replace the default French AZERTY keyboard (since I use the french language) by a swiss french QWERTZ layout. Now when I reach this dialog in the installer and try do define my new layout, the slider in the selection window doesn't appear, and clicking on any of the first layouts doesn't do anything, so I'm basically stuck there. I'm running OpenSUSE Leap 15.0 KDE on my workstation, so I tried the same thing with the previous CentOS 7.5 1804 minimal ISO, and the keyboard selection dialog works perfectly. So my intuition would tell me that there's a nasty bug in the CentOS 7.6 installer. Maybe it went unnoticed, since most folks stick to the default keyboard layout selected in their language. Any suggestions ? Cheers, Niki -- Microlinux - Solutions informatiques durables 7, place de l'église - 30730 Montpezat Site : https://www.microlinux.fr Blog : https://blog.microlinux.fr Mail : info(a)microlinux.fr Tél. : 04 66 63 10 32

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CentOS 7 as a Fibre Channel SAN Target
by Steffan A. Cline 02 Jan '20

02 Jan '20

For quite some time I’ve been using FreeNAS to provide services as a NAS over ethernet and SAN over Fibre Channel to CentOS 7 servers each using their own export, not sharing the same one. It’s time for me to replace my hardware and I have a new R720XD that I’d like to use in the same capacity but configure CentOS 7 as a Fibre Channel target rather than use FreeNAS any further. I’m doing virtualization and this will allow me to have failover from one node to the other since they’ll all be sharing the same export rather than me simply backing up to the FreeNAS server the way I am now. Does anyone know of any really good current articles that explain how to set up CentOS 7 as the target in such a configuration and also setting up CLVMd so they can all share an export over Fibre Channel from CentOS 7? Steffan A. Cline steffan(a)hldns.com 602-793-0014

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browsers slowing Centos 7 installation to a crawl
by Michael Hennebry 04 Dec '19

04 Dec '19

My video problems mentioned in a previous thread are gone, though I do not know why. Now my problem is that whenever I have a browser open and an internet connection, my Centos 7 slows to a crawl. Chromium seems to be the least bad. Sometimes it slows to the point that I cannot even move the mouse. Even switching between virtual terminals takes a while sometimes. When I get there, top generally shows me between two and five D states. I've changed service providers lately. The problem survived the change. Some sites seem to aggravate the problem. Most recently, a site tried to connect to c.amazon.adsystem.com . I got the message waiting for c.amazon.adsystem.com . I have that address in my hosts file as 127.0.0.1 . ping finds it and pings. nslookup does not: > [hennebry@localhost ~]$ nslookup c.amazon.adsystem.com > Server: 192.168.0.1 > Address: 192.168.0.1#53 > > ** server can't find c.amazon.adsystem.com: NXDOMAIN Whether the slow-to-crawl problem is related to the failure to redirect, I do not know. The former is clearly more important. Any suggestions on how to diagnose it? Any ideas on why chromium is waiting for c.amazon.adsystem.com and how I can fix it? -- Michael hennebry(a)web.cs.ndsu.NoDak.edu "Sorry but your password must contain an uppercase letter, a number, a haiku, a gang sign, a heiroglyph, and the blood of a virgin." -- someeecards

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UEFI and PXE
by isdtor 25 Oct '19

25 Oct '19

We have a working PXE setup. I've tried to adapt it to UEFI as per RHEL6 manual, but the client won't boot. Strangely, tcpdump shows that the client tries to download all files via tftp from the dhcp server rather than the tftp server (they are different). next-server is pointing to the tftp server. Any clues?

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Centos 7 on Dell Latitude E6500
by Rainer Fügenstein 09 Oct '19

09 Oct '19

Hi, I tried to install Centos7 x86_64 minimal 1503-01 from an USB flash drive on my old Dell Latitude E6500 laptop. boots up in text mode, switches text resolution, writes: Started Show Plymouth Boot Screen Reached Target Paths Reached Target Basic System. then hangs for some time, eventually starting dracut emergency shell. log says: multipathd: sdb: spurious uevent, path already in pathvec multipathd: sda: spurious uevent, path already in pathvec interesting: sdb is the internal 240GB kingston SSD drive (existing ntfs bitlocker partition recognized as sdb1) sda is the write protected USB stick, recognised as CDROM drive. 4GB rom intel 45 express chipset mobile intel GMA 4500MHD graphics intel 5100AGN wifi what to try next? any additional infos I can give you? thnx in advance. -- Best regards, Rainer mailto:rfu@oudeis.org

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/boot partition too small
by KM 02 Oct '19

02 Oct '19

First off - let me say I am not an administrator. I need to know if there is an easy way to increase my /boot partition. When I installed CentOS 6 after running 5, it was my oversight not to increase the /boot size. it's too small and I can't do yum updates. if it's not easy to actually increase it, is it safe to take a chunk in my root filesystem (like /new.boot or something) and just mount it as /boot from now on so it uses the space or is that not a good idea? I am sure I could easily copy the rpms/kernel stuff over to it and then unmounts the real /boot and mount this new area as /boot. Can you administrators let me know what you think of all this? Thanks in advance. KM

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clamd / amavisd missing socket
by Jon LaBadie 12 Sep '19

12 Sep '19

I think something along these lines appeared before but I was unable to find them. I'm on a 7.6 system, been running clamav and amavisd-new since 6 days with little problem. On a recent reboot, clamd@amavisd does not start up and fails manual start. The problem seems to be the missing socket that connects the pair, "/var/run/clamd.amavisd/clamd.socket". I believe this should be created by systemd files but I see no indication of them on my system. Anyone know which files might be missing and where to get copies? Or a work around to run clamd@amavisd and get rid of the "*** UNCHECKED ***' additions to my my Subject lines? BTW manual creation of the socket with netcat had no effect on the startup. Jon -- Jon H. LaBadie jon(a)jgcomp.com 11226 South Shore Rd. (703) 787-0688 (H) Reston, VA 20190 (703) 935-6720 (C)

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Discuss August 2019