Author: ServerOk – ServerOK

NextCloud APCu not available for local cache

Posted on October 27, 2021 by ServerOk

When trying to upgrade nextcloud, I get the following error

www-data@mail:/www/nextcloud$ php7.3 occ upgrade
An unhandled exception has been thrown:
OC\HintException: [0]: Memcache \OC\Memcache\APCu not available for local cache (Is the matching PHP module installed and enabled?)
www-data@mail:/www/nextcloud$

www-data@mail:/www/nextcloud$ php7.3 occ upgrade

An unhandled exception has been thrown:

OC\HintException: [0]: Memcache \OC\Memcache\APCu not available for local cache (Is the matching PHP module installed and enabled?)

www-data@mail:/www/nextcloud$

To fix this, you need to install APC cache.

apt install php7.3-apcu

1	apt install php7.3-apcu

For CLI, you need to edit PHP configuration file

vi /etc/php/7.2/cli/php.ini

1	vi /etc/php/7.2/cli/php.ini

at the end of the file, add

apc.enable_cli = 1

1	apc.enable_cli = 1

You can also enable apc for the current command with option

php7.3 -d apc.enable_cli=1 occ upgrade

1	php7.3 -d apc.enable_cli=1 occ upgrade

[…]

chattr: Operation not supported while reading flags

Posted on October 27, 2021 (October 27, 2021) by ServerOk

When making a file immutable with chattr command, I get the following error

[root@vps784847 vhosts]# chattr +i serverok.in.conf 
chattr: Operation not supported while reading flags on serverok.in.conf
[root@vps784847 vhosts]#

[root@vps784847 vhosts]# chattr +i serverok.in.conf

chattr: Operation not supported while reading flags on serverok.in.conf

[root@vps784847 vhosts]#

The error was due to the file I was trying to chattr being a symlink, not a real file.

[root@vps784847 vhosts]# ls -la
total 0
drwxr-xr-x. 2 root root  31 Oct 27 08:11 .
drwxr-xr-x. 7 root root 131 Jun  1 02:03 ..
lrwxrwxrwx. 1 root root  51 Jul 24 12:39 serverok.in.conf -> /var/www/vhosts/system/serverok.in/conf/nginx.conf
[root@vps784847 vhosts]#

[root@vps784847 vhosts]# ls -la

total 0

drwxr-xr-x. 2 root root 31 Oct 27 08:11 .

drwxr-xr-x. 7 root root 131 Jun 1 02:03 ..

lrwxrwxrwx. 1 root root 51 Jul 24 12:39 serverok.in.conf -> /var/www/vhosts/system/serverok.in/conf/nginx.conf

[root@vps784847 vhosts]#

To fix the error, chattr the actual file.

chattr +i /var/www/vhosts/system/serverok.in/conf/nginx.conf

1	chattr +i /var/www/vhosts/system/serverok.in/conf/nginx.conf

[…]

mount: unknown filesystem type ‘LVM2_member’.

Posted on October 26, 2021 by ServerOk

When I try to mount a partition, I get the following error

[root@sysresccd ~]# mount /dev/nvme0n1p3 /mnt
mount: /mnt: unknown filesystem type 'LVM2_member'.
[root@sysresccd ~]#

[root@sysresccd ~]# mount /dev/nvme0n1p3 /mnt

mount: /mnt: unknown filesystem type 'LVM2_member'.

[root@sysresccd ~]#

This is because the disk is LVM. First of all identify the name of the volume group and logical volume.

vgs
lvs

vgs

lvs

Example

[root@sysresccd ~]# vgs
  VG #PV #LV #SN Attr   VSize  VFree
  vg   2   3   0 wz--n- <1.82t    0 
[root@sysresccd ~]# lvs
  LV   VG Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root vg -wi-a-----   1.80t                                                    
  swap vg -wi-a----- <15.69g                                                    
  tmp  vg -wi-a-----   1.00g                                                    
[root@sysresccd ~]#

[root@sysresccd ~]# vgs

VG #PV #LV #SN Attr VSize VFree

vg 2 3 0 wz--n- <1.82t 0

[root@sysresccd ~]# lvs

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

root vg -wi-a----- 1.80t

swap vg -wi-a----- <15.69g

tmp vg -wi-a----- 1.00g

[root@sysresccd ~]#

From the above result, we found the server has 3 logical volumes. The biggest volume is root. Other volumes […]

Delayed block allocation failed for inode

Posted on October 26, 2021 by ServerOk

On a CentOS server, reading files generated IO error. On /var/log/messages, I had the following error message

Oct 25 19:19:03 mta1 kernel: EXT4-fs error (device dm-0): ext4_wait_block_bitmap:520: comm kworker/u32:2: Cannot read block bitmap - block_group = 7705, block_bitmap = 252182537
Oct 25 19:19:03 mta1 kernel: EXT4-fs (dm-0): Delayed block allocation failed for inode 39976964 at logical offset 33810 with max blocks 14 with error 5
Oct 25 19:19:03 mta1 kernel: EXT4-fs (dm-0): This should not happen!! Data will be lost

Oct 25 19:19:03 mta1 kernel: EXT4-fs error (device dm-0): ext4_wait_block_bitmap:520: comm kworker/u32:2: Cannot read block bitmap - block_group = 7705, block_bitmap = 252182537

Oct 25 19:19:03 mta1 kernel: EXT4-fs (dm-0): Delayed block allocation failed for inode 39976964 at logical offset 33810 with max blocks 14 with error 5

Oct 25 19:19:03 mta1 kernel: EXT4-fs (dm-0): This should not happen!! Data will be lost

The problem is fixed by rebooting the server into rescue mode, then running the fsck command.

[root@sysresccd ~]# fsck -y /dev/vg/root
fsck from util-linux 2.35.2
e2fsck 1.45.6 (20-Mar-2020)
/dev/mapper/vg-root contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Unconnected directory inode 61210647 (/var/cache/dnf/epel-modular-95d9a0c53e492cbd/???)
Connect to /lost+found? yes

Unconnected directory inode 61210656 (/var/cache/dnf/extras-2770d521ba03e231/???)
Connect to /lost+found? yes

Unconnected directory inode 61210668 (/var/cache/dnf/epel-6519ee669354a484/???)
Connect to /lost+found? yes

Pass 4: Checking reference counts
Inode 39845944 ref count is 1, should be 2.  Fix? yes

...
...
...

Unattached inode 61210637
Connect to /lost+found? yes

Inode 61210637 ref count is 2, should be 1.  Fix? yes

Inode 61210641 ref count is 3, should be 2.  Fix? yes

Directories count wrong for group #7474 (5, counted=0).
Fix? yes

Free inodes count wrong (120894192, counted=120894225).
Fix? yes

Padding at end of inode bitmap is not set. Fix? yes


/dev/mapper/vg-root: ***** FILE SYSTEM WAS MODIFIED *****
/dev/mapper/vg-root: 44271/120938496 files (2.2% non-contiguous), 235802671/483741696 blocks
[root@sysresccd ~]#

[root@sysresccd ~]# fsck -y /dev/vg/root

fsck from util-linux 2.35.2

e2fsck 1.45.6 (20-Mar-2020)

/dev/mapper/vg-root contains a file system with errors, check forced.

Pass 1: Checking inodes, blocks, and sizes

Pass 2: Checking directory structure

Pass 3: Checking directory connectivity

Unconnected directory inode 61210647 (/var/cache/dnf/epel-modular-95d9a0c53e492cbd/???)

Connect to /lost+found? yes

Unconnected directory inode 61210656 (/var/cache/dnf/extras-2770d521ba03e231/???)

Connect to /lost+found? yes

Unconnected directory inode 61210668 (/var/cache/dnf/epel-6519ee669354a484/???)

Connect to /lost+found? yes

Pass 4: Checking reference counts

Inode 39845944 ref count is 1, should be 2. Fix? yes

...

Unattached inode 61210637

Connect to /lost+found? yes

Inode 61210637 ref count is 2, should be 1. Fix? yes

Inode 61210641 ref count is 3, should be 2. Fix? yes

Directories count wrong for group #7474 (5, counted=0).

Fix? yes

Free inodes count wrong (120894192, counted=120894225).

Fix? yes

Padding at end of inode bitmap is not set. Fix? yes

/dev/mapper/vg-root: ***** FILE SYSTEM WAS MODIFIED *****

/dev/mapper/vg-root: 44271/120938496 files (2.2% non-contiguous), 235802671/483741696 blocks

[root@sysresccd ~]#

[…]

Nginx Rate Limiting

Posted on October 26, 2021 (October 26, 2021) by ServerOk

Nginx web server support rate-limiting with module ngx_http_limit_req_module. Block WordPress wp-login.php attack To block the WordPress wp-login.php attack, add the following to http section of your nginx.conf file.

limit_req_zone $binary_remote_addr zone=WPRATELIMIT:10m rate=2r/s;
limit_req_status 429;

1 2	limit_req_zone $binary_remote_addr zone=WPRATELIMIT:10m rate=2r/s; limit_req_status 429;

2r/2 = Lmit 2 requests per second. Inside server entry for the website, add

location ~ \wp-login.php$ {
    limit_req zone=WPRATELIMIT;
    include snippets/fastcgi-php.conf;
}

location ~ \wp-login.php$ {

limit_req zone=WPRATELIMIT;

include snippets/fastcgi-php.conf;

}

[…]

Set Static IP in RHEL 8 OVH VPS

Posted on October 22, 2021 by ServerOk

On OVH VPS running AlmaLinux 8, IPv4 IP address gets dropped. I have to connect to the server using KVM feature available in OVH control panel. I checked IP of the server with the command

ip a

ip a

It did hot show any IPv4 IP address. I checked the network configuration file

vi /etc/sysconfig/network-scripts/ifcfg-eth0

1	vi /etc/sysconfig/network-scripts/ifcfg-eth0

That had the following […]

Rocky Linux

Posted on October 21, 2021 by ServerOk

How to Convert CentOS 8 to Rocky Linux […]

How to Convert CentOS 8 to Rocky Linux

Posted on October 21, 2021 by ServerOk

You can convert your remote VPS or Dedicated Server running CentOS 8 to Rocky Linux easily by running the following commands.

dnf install wget
wget https://raw.githubusercontent.com/rocky-linux/rocky-tools/main/migrate2rocky/migrate2rocky.sh

1 2	dnf install wget wget https://raw.githubusercontent.com/rocky-linux/rocky-tools/main/migrate2rocky/migrate2rocky.sh

Now verify your system can be converted with command

bash migrate2rocky.sh -V

1	bash migrate2rocky.sh -V

If all is good, you can convert CentOS 8 to Rocky Linux with the command

bash migrate2rocky.sh -r

1	bash migrate2rocky.sh -r

[…]

Posts by ServerOk

NextCloud APCu not available for local cache

chattr: Operation not supported while reading flags

Checking NVMe Disk

mount: unknown filesystem type ‘LVM2_member’.

Delayed block allocation failed for inode

qdbus: not found

Nginx Rate Limiting

Set Static IP in RHEL 8 OVH VPS

Rocky Linux

How to Convert CentOS 8 to Rocky Linux