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How to check /tmp and /mnt/HDA_ROOT space usage via SSH terminal?

如何通过 SSH 终端检查 /tmp 和 /mnt/HDA_ROOT 的空间使用情况？

最后修订日期: 2026-03-31

Applicable Products

All QNAP NAS models running QTS / QuTS hero

Scenario

User wants to understand the purpose and typical space usage of /tmp and /mnt/HDA_ROOT on a QNAP NAS
User wants to know what is normal vs. abnormal

Solution

Both /tmp and /mnt/HDA_ROOT are system-managed directories. QTS creates and deletes their contents automatically. Under normal circumstances, you do not need to monitor or clean them manually. QTS will issue a system notification if either filesystem runs critically low on space.

/tmp is a tmpfs (RAM-based filesystem) — it is recreated fresh on every reboot and does not persist across restarts.
/mnt/HDA_ROOT is the system partition — it stores QTS system configuration, QPKG metadata, and system logs.
If space is running low, identify what is consuming the space before deleting anything — blindly removing files can break QTS services.

How to Check Space Usage

Step 1: Check Overall Filesystem Usage (df)

# Show all mounted filesystems in human-readable form
df -h

# Filter to show only /tmp and HDA_ROOT
df -h | grep -E "tmp|HDA_ROOT"

Example output:

tmpfs           991M   42M  949M   5% /tmp
/dev/md9        371M  238M  114M  68% /mnt/HDA_ROOT

Normal ranges:

/tmp: A few MB to tens of MB used is normal. Above 80% may indicate a misbehaving service or accumulated temp files.
/mnt/HDA_ROOT: ~100–300 MB used out of ~400–500 MB total is typical. Above 80% warrants investigation.

The key is not the absolute number, but whether usage is trending upward over time.

Step 2: Find What Is Consuming Space (du)

Important: Always use the -x flag with du to avoid crossing mount boundaries — this prevents du from counting files on other filesystems.

# Top-level directory sizes under /tmp
du -xh --max-depth=1 /tmp

# Top-level directory sizes under /mnt/HDA_ROOT
du -xh --max-depth=1 /mnt/HDA_ROOT

Example output (/tmp on a healthy system):

4.0K    /tmp/config
68K     /tmp/medialibrary
332K    /tmp/smart
884K    /tmp/.malware_remover
1.6M    /tmp/rssdoc
6.1M    /tmp

Example output (/mnt/HDA_ROOT on a healthy system):

8.0K    /mnt/HDA_ROOT/.qpkg
3.0M    /mnt/HDA_ROOT/archive
12M     /mnt/HDA_ROOT/ssl_lib
53M     /mnt/HDA_ROOT/.config
77M     /mnt/HDA_ROOT/.logs
117M    /mnt/HDA_ROOT/update_pkg
260M    /mnt/HDA_ROOT/

What Is Normal vs. Abnormal

Directory	Normal	Investigate If
`/tmp`	A few MB to tens of MB; fluctuates with services starting/stopping	Above 80% for extended period; single large files (> 50 MB); rapidly growing files
`/mnt/HDA_ROOT`	~100–300 MB used (~400–500 MB total); stable over time	Above 80% used and continuing to grow; `update_pkg` left over after a failed firmware update; unexpectedly large `.logs` directory

Common Causes of Abnormal Space Usage

/tmp filling up:
- A crashed or hung service writing logs to /tmp continuously
- QPKG installation that failed mid-extract, leaving large .tmp or .img files
- Third-party scripts (e.g. autorun.sh) writing output to /tmp without log rotation
/mnt/HDA_ROOT filling up:
- Failed firmware update leaving a large update_pkg file
- Excessive system log accumulation in .logs (especially .logs/network)
- Third-party QPKGs storing data in the system partition instead of a volume
- Core dump files from crashed processes
- LVM archive growth in .config/lvm/archive

Warning Signs That Require Attention

/tmp or root RAMDISK (/) stays near 100% for extended periods
/mnt/HDA_ROOT usage > 80% and continues to grow
NAS exhibits: unable to shut down or reboot properly; Web UI fails to load or services won't start; system notification: "System storage insufficient"

Does QTS Handle Cleanup Automatically?

Yes. QTS manages both directories automatically:

/tmp: Being a tmpfs, it is completely recreated on every reboot. QTS services clean up their own temp files during normal operation. A reboot is the ultimate cleanup for /tmp.
/mnt/HDA_ROOT: QTS performs log rotation (managed by syslog-ng and logrotate) and cleans up firmware update staging files after successful updates. The QTS lifecycle manages update and temp files automatically.
System alerts: If either filesystem reaches a critical threshold, QTS will generate a notification in the Notification Center (and optionally via email/push). The notification will typically say: "System storage insufficient".

Why bother with df / du at all? These commands are for debugging and troubleshooting, not daily monitoring. Use them to identify which service or QPKG is behaving abnormally, and determine whether to disable an app, restart a service, update/rollback firmware, or contact QNAP support (with logs attached).

Best practice: Under normal operation, there is no need to manually monitor or clean these directories. Only investigate when QTS generates a space alert or when troubleshooting a specific issue (e.g. shutdown hang, app installation failure).

适用产品

All QNAP NAS models running QTS / QuTS hero

场景

用户希望了解在 QNAP NAS 上/tmp和/mnt/HDA_ROOT的用途及典型空间使用情况
用户希望知道什么是正常的，什么是不正常的

解决方案

/tmp和/mnt/HDA_ROOT都是系统管理目录。QTS 会自动创建和删除其内容。在正常情况下，您无需手动监控或清理它们。如果文件系统空间严重不足，QTS 会发出系统通知。

/tmp是一个tmpfs（基于 RAM 的文件系统） —— 每次重启时都会重新创建，不会在重启后保留。
/mnt/HDA_ROOT是系统分区 —— 它存储 QTS 系统配置、QPKG 元数据和系统日志。
如果空间不足，请先识别是什么占用了空间再删除任何内容 —— 盲目删除文件可能会破坏 QTS 服务。

如何检查空间使用情况

步骤 1：检查整体文件系统使用情况 (df)

# 以人类可读的形式显示所有挂载的文件系统
df -h

# 过滤以仅显示 /tmp 和 HDA_ROOT
df -h | grep -E "tmp|HDA_ROOT"

示例输出：

tmpfs           991M   42M  949M   5% /tmp
/dev/md9        371M  238M  114M  68% /mnt/HDA_ROOT

正常范围:

/tmp: 使用几 MB 到几十 MB 是正常的。超过 80% 可能表示服务异常或临时文件积累。
/mnt/HDA_ROOT: 使用约 100–300 MB，总计约 400–500 MB 是典型的。超过 80% 需要调查。

关键不是绝对数字，而是使用量是否随着时间推移而上升。

步骤 2：查找占用空间的内容 (du)

重要：始终使用-x标志与du一起使用，以避免跨越挂载边界——这可以防止du计算其他文件系统上的文件。

# /tmp 下的优异目录大小
du -xh --max-depth=1 /tmp

# /mnt/HDA_ROOT 下的优异目录大小
du -xh --max-depth=1 /mnt/HDA_ROOT

示例输出（/tmp在健康系统上）：

4.0K    /tmp/config
68K     /tmp/medialibrary
332K    /tmp/smart
884K    /tmp/.malware_remover
1.6M    /tmp/rssdoc
6.1M    /tmp

示例输出（/mnt/HDA_ROOT在健康系统上）：

8.0K    /mnt/HDA_ROOT/.qpkg
3.0M    /mnt/HDA_ROOT/archive
12M     /mnt/HDA_ROOT/ssl_lib
53M     /mnt/HDA_ROOT/.config
77M     /mnt/HDA_ROOT/.logs
117M    /mnt/HDA_ROOT/update_pkg
260M    /mnt/HDA_ROOT/

什么是正常与异常

目录	正常	需要调查的情况
`/tmp`	几 MB 到几十 MB；随服务启动 / 停止而波动	超过 80% 持续一段时间；单个大文件（> 50 MB）；文件快速增长
`/mnt/HDA_ROOT`	~100–300 MB 已使用（总计约 400–500 MB）；随时间稳定	使用率超过 80% 并持续增长；`update_pkg`在固件更新失败后剩余；意外的大型`.logs`目录

异常空间使用的常见原因

/tmp 填满：
- 崩溃或挂起的服务持续将日志写入 /tmp
- QPKG 安装中途失败，留下大型.tmp或.img文件
- 第三方脚本（例如autorun.sh）将输出写入 /tmp 而不进行日志轮替
/mnt/HDA_ROOT 填满：
- 失败的固件更新留下大型update_pkg文件
- 系统日志在.logs中过多累积（尤其是.logs/network）
- 第三方 QPKG 将数据存储在系统分区而不是卷中
- 崩溃进程的核心转储文件
- LVM 归档在.config/lvm/archive中增长

需要注意的警告信号

/tmp或根 RAMDISK (/) 长时间接近 100%
/mnt/HDA_ROOT使用率 > 80% 并继续增长
NAS 表现：无法正常关机或重启；Web UI 无法加载或服务无法启动；系统通知：“系统存储不足”

QTS 是否自动处理清理工作？

是的。QTS 会自动管理这两个目录：

/tmp：作为一个 tmpfs，它在每次重启时都会重建。QTS 服务在正常操作期间会清理自己的临时文件。重启是 /tmp 的较终清理方式。
/mnt/HDA_ROOT：QTS 执行日志轮换（由syslog-ng和logrotate管理）并在成功更新后清理固件更新暂存文件。QTS 生命周期自动管理更新和临时文件。
系统警报：如果任一文件系统达到临界阈值，QTS 将在通知中心中生成通知（也可以通过电子邮件 / 推送通知）。通知通常会说："系统存储不足"。

为什么要麻烦df / du？这些命令用于调试和故障排除，而不是日常监控。使用它们来识别哪个服务或 QPKG 行为异常，并决定是否禁用应用程序、重启服务、更新 / 回滚固件，或联系 QNAP 支持（附上日志）。

较佳实践：在正常操作下，无需手动监控或清理这些目录。只有在 QTS 生成空间警报或排查特定问题时（例如关机挂起、应用安装失败）才进行调查。

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