Disk health (smartctl)
Dedicated server disks eventually fail. SMART (Self-Monitoring, Analysis and Reporting Technology) reports reallocated sectors, read errors, and SSD wear before total failure. smartctl is part of the smartmontools package.
Prerequisites
- Linux dedicated server with root access
- SATA/SAS/NVMe disks recognized by controller (hardware RAID may hide SMART — see below)
- No destructive tests during production hours without a maintenance window
Installation
sudo apt update
sudo apt install -y smartmontools
sudo systemctl enable --now smartd
Identify disks
lsblk -d -o NAME,SIZE,MODEL,ROTA
sudo smartctl --scan
Example paths:
| ------ | -------- |
|---|---|
| SATA | /dev/sda |
| NVMe | /dev/nvme0 |
First SMART read
sudo smartctl -a /dev/sda
sudo smartctl -a /dev/nvme0
Critical attributes (HDD):
| ---------- | --------------- |
|---|---|
Reallocated_Sector_Ct |
Remapped bad sectors — > 0 to watch |
UDMA_CRC_Error_Count |
Often faulty cable/SAS |
SSD NVMe: check Percentage Used, Media Errors, Available Spare.
Short test (non-destructive)
sudo smartctl -t short /dev/sda
# wait ~2 min
sudo smartctl -a /dev/sda | tail -20
Long test (HDD, several hours):
sudo smartctl -t long /dev/sda
Plan a maintenance window — high I/O.
smartd: automatic alerts
Edit /etc/smartd.conf:
/dev/sda -a -o on -S on -s (S/../.././02|L/../../6/03) -m root@localhost
/dev/nvme0 -a -o on -S on -m root@localhost
-s: scheduled tests (short daily, long weekly)-m: email (configurepostfixor HolyCloud relay)
sudo systemctl restart smartd
sudo smartctl -i /dev/sda | grep -i smart
Hardware RAID (MegaRAID, etc.)
Physical disk may be /dev/bus/0 — use controller tools:
# MegaRAID example
sudo apt install -y megacli
# or storcli from vendor
Ask HolyCloud support for RAID model for exact smartctl -d megaraid,N -a /dev/sda command.
Quick interpretation
sudo smartctl -H /dev/sda
| ---------- | -------- |
|---|---|
FAILED |
Immediate backup, disk replacement ticket |
| Inconsistent data | Cable, backplane, controller |
Logging
sudo smartctl -a /dev/sda > /root/smart-sda-$(date +%F).txt
Keep monthly history to see counter drift.
Dedicated server best practices
- Monitor all RAID disks, not only the visible logical volume.
- Pair SMART with off-server backups (S3, another DC).
- After HolyCloud disk replacement, rerun
smartctl -t short.
Troubleshooting
| ---------- | ------- |
|---|---|
| SMART Disabled | smartctl -s on /dev/sda |
| Device open failed | Disk in RAID without -d option |
| NVMe « unknown» | Update smartmontools |
Need help?
Open a ticket with full smartctl -a output, disk serial (panel / IPMI), and slot for warranty replacement.