Analysis of Disk Issues

Analysis of Disk Issues

Disk problems can threaten any modern business with the loss of critical information or disruptions in database operations. It seems almost everyone has encountered such issues. While modern storage systems (SANs) effectively address most data security concerns and optimize input/output operations, they cannot fully prevent problems without diligent monitoring. Additionally, it’s crucial to keep a close watch on available disk space, as overfilling poses a significant risk.

In this publication, we’d like to share some professional tips to help you tackle these challenges.

Why Check Partitions and Disks for Errors?

At the simplest level, errors on a partition or disk can lead to reduced performance or issues with database management system (DBMS) files, such as the inability to expand a data file or transaction log. If critical processes depend on a faulty partition or disk, the efficiency of the entire business operation may be compromised, potentially resulting in a complete shutdown. Regularly inspecting the condition of your disks and storage systems is essential to avoid such risks!

What Types of Errors Can Occur on a Partition or Disk? What Causes Them?

Disk errors typically fall into two categories: physical and logical.

• • Physical Errors
    These involve actual hardware damage to the disk. HDDs, with their mechanical parts, can wear out over time, and even SSDs are not immune to external damage or failure during an accident. Impacts, overheating, and natural wear and tear can corrupt data—often irreversibly, though individual sectors can sometimes be salvaged.
  • Logical Errors
    These are usually software-related and are less often permanent. They occur much more frequently than physical errors but can render specific sectors of the disk unusable. Common causes include software crashes, formatting errors, and disk overfilling.

We won’t delve into physical problems here: unless your equipment faces fire, accidents, or physical tampering, such issues are unlikely to affect you.

Monitoring Free Disk Space

Available disk space is a critical metric in any monitoring system, but sometimes it requires manual and detailed evaluation. The simplest way to check free space locally is through file explorer or by using scripts in SQL Server Management Studio (SSMS). However, these methods may not always be convenient, especially if disks are managed as directories rather than logical drives. This is where the Zabbix monitoring system proves invaluable.

Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.

Missing DisksAvoid Disk Overflows!

To prevent future headaches from disk issues, it’s crucial to monitor disk usage diligently to avoid overflows. When a disk becomes full, the resulting problems depend on its function and can include the following:

• • System Disk: Server freezes or crashes, potentially resulting in a blue screen.
  • Transaction Log Disk: The database will stop accepting new transactions, causing errors in the application. If an overflow occurs during a large transaction, it will fail and roll back.
  • TempDB Disk: The DBMS may freeze. If a large transaction using TempDB was in progress, it will fail and roll back, potentially releasing space quickly.
  • Data File Disk: The database will start overwriting old pages with new data. This usually leads to rapid database corruption, rendering it unusable. This scenario must be avoided at all costs! (If the database has files on other disks that can grow, this situation is safe, though maintenance operations might generate errors in the logs.)
  • User File Disk: Applications may experience functionality issues.

What to Do if a Disk Overflows?

• Place new database files on other available free disks.
• Compress or move neighboring files on the full disk.
• Stop processes that caused the overflow

Missing Disks

“Missing disk” is a common alert with various potential causes:

• • The disk was disconnected.
  • The disk was renamed.
  • A disk failure occurred, preventing the monitoring system from collecting data.

To check the status of all disks, you can use the built-in Disk Management utility. Launch it with the command diskmgmt.msc or by right-clicking the Start menu.

This utility displays physical disks, their statuses, and partitions. It also allows you to reassign drive letters to partitions if needed.