Rocky Linux Storage — LVM, Software RAID (mdadm), Samba & NFS Guide

LVM Layer Stack
1
Physical Volume (PV)
Raw block devices: /dev/sdb, /dev/sdc
2
Volume Group (VG)
Pool of PVs — vg_data (all disks combined)
3
Logical Volume (LV)
Flexible partitions: lv_db, lv_logs, lv_backup
4
Filesystem
ext4 or XFS formatted on top of each LV
5
Mount Point
/var/lib/mysql, /var/log, /backup

Storage · LVM

LVM — Logical Volume Manager

LVM is the standard storage abstraction layer on Rocky Linux. It lets you create, resize, snapshot, and move storage without rebooting — essential for production database servers where downtime is not an option.

Create PV → VG → LV → Filesystem

# Initialise physical volumes

[root@rocky ~]$ pvcreate /dev/sdb /dev/sdc

# Create volume group

[root@rocky ~]$ vgcreate vg_data /dev/sdb /dev/sdc

# Create logical volumes

[root@rocky ~]$ lvcreate -L 100G -n lv_mysql vg_data

[root@rocky ~]$ lvcreate -L 20G -n lv_logs vg_data

# Format and mount

[root@rocky ~]$ mkfs.xfs /dev/vg_data/lv_mysql

[root@rocky ~]$ mount /dev/vg_data/lv_mysql /var/lib/mysql

Online resize and snapshot

# Extend an LV online (XFS grows live)

[root@rocky ~]$ lvextend -L +50G /dev/vg_data/lv_mysql

[root@rocky ~]$ xfs_growfs /var/lib/mysql

# Create snapshot before risky migration

[root@rocky ~]$ lvcreate -L 10G -s -n snap_mysql /dev/vg_data/lv_mysql

# Revert if something goes wrong:

[root@rocky ~]$ lvconvert --merge /dev/vg_data/snap_mysql

Storage · RAID

Software RAID with mdadm

Rocky Linux includes mdadm for Linux software RAID. For most workloads, RAID 1 (mirror) or RAID 5/6 (stripe with parity) gives the best balance of redundancy and performance — without expensive hardware RAID controllers.

Create RAID 1 mirror (2 disks)

[root@rocky ~]$ dnf install -y mdadm

# Create RAID 1 from /dev/sdb and /dev/sdc

[root@rocky ~]$ mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb /dev/sdc

# Save config and format

[root@rocky ~]$ mdadm --detail --scan >> /etc/mdadm.conf

[root@rocky ~]$ mkfs.xfs /dev/md0 && mount /dev/md0 /data

Monitor RAID health

[root@rocky ~]$ cat /proc/mdstat

md0 : active raid1 sdb[0] sdc[1]

102400 blocks super 1.2 [2/2] [UU]

[root@rocky ~]$ mdadm --detail /dev/md0

RAID Level Comparison

Level	Redundancy	Usable Space	Best For
RAID 0	None	100%	Speed only
RAID 1	✔ Mirror	50%	Boot disks, small DBs
RAID 5	✔ 1 disk	~67–75%	General storage
RAID 6	✔ 2 disks	~50–67%	Large arrays
RAID 10	✔ Mirror+Stripe	50%	High-perf databases

⚠️

RAID ≠ Backup: A RAID array protects against disk failure but not against accidental deletion, filesystem corruption, or ransomware. Always combine RAID with a separate backup strategy.

Replace a Failed Disk

Hot-replace failed drive

# Mark disk as failed

[root@rocky ~]$ mdadm /dev/md0 --fail /dev/sdc

[root@rocky ~]$ mdadm /dev/md0 --remove /dev/sdc

# (physically replace disk, then:)

[root@rocky ~]$ mdadm /dev/md0 --add /dev/sdc

# Resync begins automatically

Windows ↔ Rocky Linux File Share

Windows Client \\rocky-server\shared

SMB/CIFS protocol

Samba (smbd) Handles file/print shares

Runs on Rocky Linux

Winbind (optional) AD domain authentication

Active Directory join

SELinux samba_share_t context required

Rocky Linux security layer

Firewalld Port 445, 137-139 open

Zone-based filtering

Storage · Samba

Samba — Windows File Sharing

Samba implements SMB/CIFS protocol so Windows clients can mount Rocky Linux directories as network drives. It also supports Active Directory domain membership for centralised authentication.

Install Samba and configure share

[root@rocky ~]$ dnf install -y samba samba-common samba-client

[root@rocky ~]$ systemctl enable --now smb nmb

/etc/samba/smb.conf — share definition

[global]

workgroup = WORKGROUP

server string = Rocky Linux File Server

security = user

map to guest = bad user

[shared]

path = /data/shared

browseable = yes

writable = yes

valid users = @smbusers

create mask = 0664

directory mask = 0775

SELinux + Firewall for Samba

[root@rocky ~]$ chcon -Rt samba_share_t /data/shared

[root@rocky ~]$ setsebool -P samba_enable_home_dirs 1

[root@rocky ~]$ firewall-cmd --permanent --add-service=samba

[root@rocky ~]$ smbpasswd -a username

Rocky Linux Storage Management