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Storage

Resizing Disk

[root@host ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        7.6G     0  7.6G   0% /dev
tmpfs           7.6G  8.0K  7.6G   1% /dev/shm
tmpfs           7.6G  759M  6.9G  10% /run
tmpfs           7.6G     0  7.6G   0% /sys/fs/cgroup
/dev/sda1       151G   22G  123G  16% /
/dev/sdc        500G  247G  254G  50% /var/lib/pgsql
tmpfs           1.6G     0  1.6G   0% /run/user/1001
[root@host ~]# resize2fs /dev/sdc
resize2fs 1.42.9 (28-Dec-2013)
resize2fs: Bad magic number in super-block while trying to open /dev/sdc
Couldnt find valid filesystem superblock.
[root@host ~]# xfs_growfs /dev/sdc
meta-data=/dev/sdc               isize=512    agcount=4, agsize=32768000 blks
        =                       sectsz=512   attr=2, projid32bit=1
        =                       crc=1        finobt=1 spinodes=0
data     =                       bsize=4096   blocks=131072000, imaxpct=25
        =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=64000, version=2
        =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 131072000 to 175636480
[root@host ~]# 
[root@host ~]# 
[root@host ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        7.6G     0  7.6G   0% /dev
tmpfs           7.6G  8.0K  7.6G   1% /dev/shm
tmpfs           7.6G  759M  6.9G  10% /run
tmpfs           7.6G     0  7.6G   0% /sys/fs/cgroup
/dev/sda1       151G   22G  123G  16% /
/dev/sdc        670G  247G  424G  37% /var/lib/pgsql
tmpfs           1.6G     0  1.6G   0% /run/user/1001
[root@host ~]#

File System Check Loop

You start up CentOS and it wants to do a File System check. You do the check, reboot and it happens again. Try the following:

  1. Put a CentOS disk into the DVD-Rom
  2. Start Rescue Mode
  3. Type the following commands:
chroot /mnt/sysimage
badblocks -sv /dev/sdax -o <file_name_here>
e2fsck -t ext3 -l <file_name_here> /dev/sdax
vi /etc/fstab
  comment out /dev/sdax before booting the server again

Formatting USB Flash Drive

  • vFAT (FAT32): mkfs.vfat
  • NTFS: mkfs.ntfs
  • EXT4: mkfs.ext4
# Format
mkfs.ext4 -L CALEB /dev/sdx

# Show information about the USB flash
parted /dev/sdx print

# Mound the flash
mount -t ext4 /dev/sdx1 /mnt/CALEB

Repairing Grub

You boot up Linux machine (CentOS) and only "grub _" displays on the screen. You can try:

  1. Boot from Linux live CD/USB
  2. Start in Rescue Mode
  3. Run commands
chroot /mnt/sysimage
sbin/grub-install
mount
reboot

Mount

# install cifs-utils
apt-get install cifs-utils

# /etc/fstab
//server/data /mnt/data cifs credentials=/root/.smbcredentials,vers=1.0,iocharset=utf8,sec=ntlm 0 0

mount -a

Mount USB Flash Disk

# Create folder for mounting
mkdir -p /media/USB

# List /dev/
ls /dev/

# Insert Flash now, then list /dev/ again, if flash is sdb:
mount -t vfat /dev/sdb1 /media/USB

# List contents of /media/USB
# If dir contains System Volume Information, you good
# When you are done, to safely remove:
umount /media/USB

iostat

sudo apt-get install sysstat
iostat -d 2 /dev/sda

DRBD

### CONFIGURATION
# After deploying DRBD through Ansible:
# Initialize the metadata
drbdadm create-md data

# Start the resource
drbdadm up data

# Set primary or standby
drbdadm primary --force data
drbdadm secondary --force data

mkfs.ext3 /dev/drbd1
mount /dev/drbd1 /mnt/data

# Upgrade to DRBD v9
sudo add-apt-repository ppa:linbit/linbit-drbd9-stack
sudo apt update -y && sudo apt upgrade -y


### AFTER REBOOT / POWER FAILURE
# Dont panic your data is in /dev/drbd1, just need to mount it
sudo drbdadm up data

# on primary only
sudo drbdadm primary --force data

# Mount drbd1 (where the data is!)
sudo mount /dev/drbd1 /mnt/data

# Start docker container from compose
cd /etc/docker/owncloud/
sudo docker-compose up -d

# Restart deluge container to see the data again
sudo docker restart deluge

ZFS

# Install ZFS
sudo apt install zfsutils-linux

# Check which disks to use
fdisk -l

# Create the pool (data will be wiped!)
sudo zpool create tank /dev/sdb /dev/sdc

# Check Status
sudo zpool status

# Create ZFS Volume in pool or tank
sudo zfs create -V 3486gb tank/vol

GlusterFS

# Install GlusterFS
apt install glusterfs-server -y

# Add servers to hosts file (to not rely on DNS)
nano /etc/hosts

# Create Gluster Volume
gluster volume create gv0 server:/data server2:/data force

# Start Gluster Volume
gluster volume start gv0

Badblocks

  • You can use a Linux boot CD to repair a Windows NTFS disk fault.
  • If no filesystems are specified on the command line, and the -A option is not specified, fsck will default to checking filesystems in the /etc/fstab serial.
  • This can take several hours depending on the speed of your system and the size and speed of your disk.
  • unmount the disk first using sudo fsck -pcfv /dev/sda. This fsck command forces automatic bad block checking and it automatically marks all known bad sectors as bad too.
  • If you're booting back into Linux, make sure that smartmontools is installed and enabled with sudo apt-get install smartmontools.
  • Enable "SMART" in your BIOS if it isn't already.
  • Run an extended offline test with sudo smartctl --test=long /dev/sda
  • To see a nice overall view of system health: sudo smartctl -a /dev/sda

Linux Harddrive

  1. Put a CentOS disk into the DVD-Rom
  2. Start Rescue Mode
  3. Type the following commands:
fdisk -l
mkdir /mnt/boot
mount /dev/hdb1 /mnt/boot
df -h
cd /mnt/boot
badblocks -sv /dev/sdax -o <file_name_here>
e2fsck -t ext3 -l <file_name_here> /dev/sdax

Windows Harddrive

Warning

This is not a good idea!

  1. Plug the ntfs disk into a Linux box
  2. Boot off the Linux box
  3. Type the following commands:
yum install ntfs-3g ntfs-config ntfsprogs testdisk
ln -s /usr/bin/ntfsfix /usr/sbin/fsck.ntfs
ln -s /usr/bin/ntfsfix /usr/sbin/fsck.ntfs-3g
fdisk -l
mkdir /mnt/boot
mount /dev/hdbx /mnt/boot
df -h
cd /mnt/boot
badblocks -sv /dev/hdbx -o <file_name_here>
e2fsck -t ext3 -l <file_name_here> /dev/hdbx

MDADM

# Add entry to fstab to automount
nano /etc/fstab
  /dev/md0        /media/data     ext4 defaults 0 0

# Ensure that the mountpoint exists
mkdir /media/data

# Create a FS on the array if not done already
mkfs.ext4 /dev/md0

# Mount the FS
mount /dev/md0 /media/data

# Or mount all
mount -a