Whether it is a traditional file server, NAS, SAN storage, or modern distributed object storage, its core tasks are inseparable from the reasonable scheduling of space resources and the continuous availability guarantee. However, when the storage space is close to exhaustion, problems such as system performance degradation, business interruption, and data write failure are very likely to occur, and in serious cases, even business data loss. Therefore, establishing a complete set of "automatic warning mechanism for insufficient space" is a key link in operation and maintenance guarantee.

　　Why do you need to monitor storage space and set warnings?

　　1. Prevent system crashes and application write failures

　　When the storage space is exhausted, the system may have problems such as database inability to write, log service suspension, virtualization platform snapshot failure, user inability to upload files, and container mounting volume errors.

　　2. Reduce the risk of emergency expansion

　　Through early warning, time can be reserved for operation and maintenance operations such as space cleanup, disk expansion, and load migration to avoid temporary handling of problems during business peak periods.

　　3. Ensure business continuity

　　Continuous monitoring can help administrators understand disk usage trends, predict future capacity requirements in combination with data growth models, and adjust deployment in advance.

　　Principles of space monitoring and automatic warning

　　The monitoring system regularly collects disk usage data of the storage server (such as df output) to determine whether the usage rate of the disk partition exceeds the preset threshold. Once the alarm condition is met, the alarm event is triggered and the relevant responsible person is notified through email, SMS, Webhook, corporate WeChat, etc.

　　Basic elements include:

　　Data collector: collects information such as disk capacity, used/available space, etc.

　　Monitoring threshold rules: determine whether space occupancy exceeds the standard

　　Alarm processor: triggers alarms and pushes notifications

　　Trigger action: executes custom scripts (clean cache, restart service, etc.)

　　Recommendations for selecting common monitoring tools

　　Depending on the storage architecture and team technology stack, the following mainstream tools can be used to achieve automatic monitoring and warning:

　　1. Zabbix: open source full-featured monitoring system, supports Linux disk space custom thresholds, triggers/alarm media, chart display and trend analysis.

　　2. Prometheus combined with Grafana: a modern cloud-native monitoring solution. The Node Exporter plug-in can collect file system data, use Alertmanager to configure thresholds and alert push, and combine with Grafana to visualize capacity trends.

　　3. Shell scripts with crontab (lightweight solution), no need to install a monitoring system, use df, awk, mail and other commands to achieve local regular scanning and email reminders, suitable for small environments or single servers.

　　how to choose the appropriate alarm threshold?

　　Threshold setting cannot be a one-size-fits-all approach, and should be formulated in combination with factors such as disk capacity, business characteristics, and data growth rate. The following are general recommendations:

　　Space remaining < 30%: Remind attention, arrange cleanup or expansion plan

　　Space remaining < 20%: Intermediate alarm, prompt to clean cache or transfer cold data

　　Space remaining < 10%: Advanced warning, suggest immediate expansion or execute cleanup script

　　Space remaining < 5%: Serious alarm, trigger automated emergency processing flow

　　In addition, the threshold trigger point should be appropriately relaxed for disk write-intensive services such as database servers and log servers, and intervene in advance.

　　Avoiding false alarms and optimization suggestions

　　1. Exclude temporary mount points or backup directories: avoid false alarms for non-critical partitions;

　　2. Set up a recovery alarm mechanism: actively push "recovered" information after space recovery to avoid administrator misjudgment;

　　3. Combine historical trend analysis: analyze the space consumption rate through charts to assist in predicting the time point for expansion;

　　4. Enable regular cleanup for log-type disks: it is recommended to use logrotate to automatically compress or delete old logs to avoid meaningless growth;

　　5. Mount additional partitions or use cloud hard disks to expand capacity: the production environment should try to use hot-expandable mounting methods to avoid restarting the server.

　　Monitoring the disk space of the storage server and setting automatic warnings is one of the basic means to ensure stable system operation and data security. Whether you are using an enterprise-level storage array, a virtual server, or a bare metal physical server, you must establish a complete warning mechanism to avoid the passive situation of "finding it when it is full". By making reasonable selections, setting scientific thresholds, and improving the alarm push process, we can effectively improve operation and maintenance efficiency, ensure business continuity, and provide data support for decisions such as system expansion and migration.