Discuss December 2021

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44 participants
40 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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Problems with CentOS 8 kickstart
by Hooton, Gerard 23 Jun '25

23 Jun '25

Hi All, I am having problems with a kickstart install of CentOS 8 When I try to do a completely automated install using PXE/UEFI it get to the point where it reads the kickstart config file. Then I see the following message "kickstart install Started cancel waiting for multipath siblings for nvme0n1" This is what I have in the kickstart file # Clear the Master Boot Record zerombr # Partition clearing information clearpart --all --initlabel autopart --nohome --type=lvm --fstype=xfs ================ When I install from a USB drive it works OK and I have the following in /dev/disk/by-id lrwxrwxrwx. 1 root root 13 Jul 5 10:28 nvme-SAMSUNG_MZVL2512HCJQ-00BL7_S64KNE0R161810 -> ../../nvme0n1 lrwxrwxrwx. 1 root root 13 Jul 5 10:28 nvme-eui.002538b11102f46d -> ../../nvme0n1 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 wwn-eui.002538b11102f46d-part3 -> ../../nvme0n1p3 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 nvme-SAMSUNG_MZVL2512HCJQ-00BL7_S64KNE0R161810-part3 -> ../../nvme0n1p3 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 nvme-eui.002538b11102f46d-part3 -> ../../nvme0n1p3 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 lvm-pv-uuid-5Dg4mg-saHa-hJJ6-n5a8-MxBS-gdFi-5jPoNn -> ../../nvme0n1p3 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 wwn-eui.002538b11102f46d-part2 UNG_MZVL2512HCJQ-0-> ../../nvme0n1p2 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 nvme-SAMSUNG_MZVL2512HCJQ-00BL7_S64KNE0R161810-part2 -> ../../nvme0n1p2 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 nvme-eui.002538b11102f46d-part2 -> ../../nvme0n1p2 drwxr-xr-x. 2 root root 400 Jul 5 10:28 . lrwxrwxrwx. 1 root root 15 Jul 5 10:28 wwn-eui.002538b11102f46d-part1 -> ../../nvme0n1p1 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 nvme-SAMSUNG_MZVL2512HCJQ-00BL7_S64KNE0R161810-part1 -> ../../nvme0n1p1 lrwxrwxrwx. 1 root root 15 Jul 5 10:28 nvme-eui.002538b11102f46d-part1 -> ../../nvme0n1p1 lrwxrwxrwx. 1 root root 10 Jul 5 11:07 dm-uuid-LVM-qQok4M7AOo1TxZZ42GwZcbuVNBs0hnkKtEdtLjwJQyIdxJcSvPv8TEAjwYGMv6yU -> ../../dm-0 lrwxrwxrwx. 1 root root 10 Jul 5 11:07 dm-uuid-LVM-qQok4M7AOo1TxZZ42GwZcbuVNBs0hnkKAooqrczySYJyiHvUAUji9oScPN2cVi7J -> ../../dm-1 lrwxrwxrwx. 1 root root 10 Jul 5 11:07 dm-name-cs_uews027-swap -> ../../dm-1 lrwxrwxrwx. 1 root root 10 Jul 5 11:07 dm-name-cs_uews027-root -> ../../dm-0 lrwxrwxrwx. 1 root root 10 Jul 5 11:07 dm-uuid-LVM-qQok4M7AOo1TxZZ42GwZcbuVNBs0hnkK5HZXbR2ow5xKGuD7jVe4UPzZm2qRLLXI -> ../../dm-2 lrwxrwxrwx. 1 root root 10 Jul 5 11:07 dm-name-cs_uews027-home -> ../../dm-2 It's looks like that I am not doing the disk drive stuff in the config file correctly. -- Gerard Hooton. Senior Technical Officer School of Engineering. University College Cork. College Road. Cork. Ireland. Loc8: WDR-04-60G Tel: +353 21 4902296 Mobile: +353 852813491

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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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OT:: Multiple PHP versions
by TE Dukes 22 Aug '22

22 Aug '22

Hello, Been trying to get multiple versions of PHP on a CentOS 7 machine, off and on for the past couple months. I have followed 5 or 6 different howtos but none work. They are very similar and they seems to be done on a fresh install as most do an apache install is the steps. I setup two virtualhosts one for PHP5.6 and one for PHP 7.4. When I create a file with phpinfo, it reports back 5.6.xxx on both sites. So, I'm wondering if I need to remove the existing PHP version that is included with CentOS? Any suggestions or a better way to do this? TIA

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Introducing CentOS Stream 9
by Johnny Hughes 05 Apr '22

05 Apr '22

Rich Bowen has posted a blog entry "Introducing CentOS Stream 9" https://blog.centos.org/2021/12/introducing-centos-stream-9/ More details here: https://centos.org/stream9/ Thanks, Johnny Hughes

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Qemu - enabling "bridge mode" for primary physical interface for VMs
by Lists 19 Jan '22

19 Jan '22

I have a physical host with a single physical network adapter. I want to host several VMs on host. (guest1 - guest4) The guest systems are accessible via 192.168.122.* as is the default with qemu/virsh. There are 4 IP addresses being routed to the primary interface on host. I can set up an alias for the NIC and "see" these ip addresses. I understand that it's possible to allow the 4 VM guest systems to each have a "direct" fixed IP address and access the addresses \via the host network adapter, while the host retains its fixed IP. I've been googling like crazy and there is a lot of stale and conflicting information. Has anybody here done this successfully? Host and all guests are running CentOS 8. Thanks. Ben S

3 5

NFS Share fails to mount at boot time
by Felix Natter 15 Jan '22

15 Jan '22

hello fellow CentOS Users, on Scientific Linux 7 (_very_ similar to CentOS7), I get this when trying to mount NFS Shares (exported from Synology NAS) automatically at boot time: [root@HOST ~]# journalctl -b 0 | grep NAS[20] Jul 01 13:32:09 HOST systemd[1]: Mounting /mnt/NAS0... Jul 01 13:32:09 HOST systemd[1]: Mounting /mnt/NAS2... Jul 01 13:32:09 HOST systemd[1]: mnt-NAS0.mount mount process exited, code=exited status=32 Jul 01 13:32:09 HOST systemd[1]: Failed to mount /mnt/NAS0. Jul 01 13:32:09 HOST systemd[1]: Unit mnt-NAS0.mount entered failed state. Jul 01 13:32:09 HOST systemd[1]: mnt-NAS2.mount mount process exited, code=exited status=32 Jul 01 13:32:09 HOST systemd[1]: Failed to mount /mnt/NAS2. Jul 01 13:32:09 HOST systemd[1]: Unit mnt-NAS2.mount entered failed state. I read that enabling NetworkManager-wait-online.service can mitigate that, but it's already enabled: [root@HOST ~]# systemctl list-unit-files|grep wait chrony-wait.service disabled NetworkManager-wait-online.service enabled plymouth-quit-wait.service disabled /mnt/NAS2 is defined in /etc/fstab (/mnt/NAS0 is mounted analogously): NAS2HOST:/volume1/export/ /mnt/NAS2 nfs rw,vers=3,soft,bg,intr 0 0 This does not always occur, and it seems to be a race condition, because it did not occur a few months ago, before we moved offices (when only the networking changed slightly). Of course, once the computer is booted, I can always mount the shares without problems. Does someone have an idea? Many Thanks and Best Regards, -- Felix Natter

3 4

how to clear out /var/cache?
by Fred 04 Jan '22

04 Jan '22

Is it safe to just remove files from /var/cache on a running system, or is there a correct procedure for doing that? Mine has hit over 3 gigs, making it one of the larger directories in /, which is running low on space. I've hit all the low-hanging fruit I can find and now I come to things like /var/cache, and I don't know what to do about such. Thanks in advance! Fred

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Re: [CentOS] how to clear out /var/cache?
by Fred 31 Dec '21

31 Dec '21

Skylar: that's more or less what I've been doing, looking for huge things in /. Kenneth: the latest version of kdirstat appears to now be named qdirstat, no kde bits required. it is certainly a handy way to quickly find the disk space sinks. Thanks for the pointer. but I still don't know the proper way to clear out a lot of this stuff. I certainly don't want to hose my system. It is C7, up to date, and it has been running for at least five years with partitions as they are set now: / is 50 gigs. had a popup message this morning telling me that / was nearly full. found it with 2 gigs free. sounds as if something has been slowly eating away at the space. I could use gparted to rearrange things, making / bigger, but as it has been going for five years, it strikes me that it more likely needs a lot of garbage collection to be done. I've manually cleaned up some detritus, it now reports 3.7G free which should hold me for a little while. So, can anyone advise me on what is and what is not safe to whack/delete from the root partition? Thanks! Fred On Thu, Dec 30, 2021 at 7:16 PM Kenneth Porter <shiva(a)sewingwitch.com> wrote: > --On Thursday, December 30, 2021 6:20 PM -0500 Fred <fred.fredex(a)gmail.com> > > wrote: > > > Mine has hit over 3 gigs, making it one of the larger directories in /, > > which is running low on space. I've hit all the low-hanging fruit I can > > find and now I come to things like /var/cache, and I don't know what to > do > > about such. > > Have you run KDirStat to find the disk pigs? I regularly use its Windows > derivative, WinDirStat. > > <http://kdirstat.sourceforge.net/> > <https://windirstat.net/> > > I wish there was a web-based version for headless servers without X > libraries. > > _______________________________________________ > CentOS mailing list > CentOS(a)centos.org > https://lists.centos.org/mailman/listinfo/centos >

3 2

Delete local user/group but not LDAP one
by Felix Natter 30 Dec '21

30 Dec '21

Dear fellow linux users, I have a computer with a local user X that shadows an LDAP user of the same name (and group). I know I can use: userdel X groupdel X but how do I make sure that the LDAP is not changed, and only the local user/group is deleted? This is very critical. Many Thanks and Best Regards, -- Felix Natter

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Discuss December 2021