Applicable Products
- QNAP NAS using QTS with HBS3 Time Machine service
Scenario
A user set the Time Machine backup folder maximum size too high in HBS3 (3 TB) and wants to reduce it to 2 TB after cleaning old backups.
The main concern is whether lowering the limit in HBS3 is safe and whether it can cause backup issues.
Solution
Preconditions
- Check current actual Time Machine usage from macOS/NAS and make sure it is at or below the new target limit.
- Confirm your Time Machine target is the HBS3-managed shared-folder path (QTS behavior).
Step-by-Step
- Open HBS3 on the NAS.
- Go to the Time Machine settings page where backup folder and maximum capacity are configured.
- Change the maximum size from the old value (for example, 3 TB) to the new value (for example, 2 TB).
- Save the setting.
- Trigger or wait for the next Time Machine backup cycle from the Mac.
- Verify backup continues normally.
What to Expect After Reducing the Limit
- Lowering the max value does not immediately delete all old backup data by itself.
- Time Machine manages retention/purging over time based on available quota and backup behavior.
- If usage is still above the new limit, backup may pause/fail until enough old snapshots are purged.
Warning
Do not reduce the limit too aggressively. Keep headroom for upcoming incremental backups to avoid frequent quota-pressure events.
Validation Checklist
- New max-size value is visible in HBS3 Time Machine settings.
- Mac can still run Time Machine backup without authentication or destination errors.
- NAS storage usage trend stabilizes and old versions are purged as expected over subsequent cycles.
适用产品
- QNAP NAS using QTS with HBS3 Time Machine service
场景
用户在 HBS3 中将 Time Machine 备份文件夹的较大大小设置得过高（3 TB），希望在清理旧备份后将其减少到 2 TB。
主要关注点是降低 HBS3 中的限制是否安全，以及是否会导致备份问题。
解决方案
前提条件
- 从 macOS/NAS 检查当前实际的 Time Machine 使用情况，并确保其在新的目标限制之下或相等。
- 确认您的 Time Machine 目标是 HBS3 管理的共享文件夹路径（QTS 行为）。
步骤
- 在 NAS 上打开HBS3。
- 进入 Time Machine 设置页面，在那里配置备份文件夹和较大容量。
- 将较大大小从旧值（例如 3 TB）更改为新值（例如 2 TB）。
- 保存设置。
- 触发或等待 Mac 的下一个 Time Machine 备份周期。
- 验证备份正常继续。
降低限制后的预期
- 降低较大值不会立即删除所有旧备份数据。
- Time Machine 会根据可用配额和备份行为随时间管理保留 / 清除。
- 如果使用量仍高于新限制，备份可能会暂停 / 失败，直到足够的旧快照被清除。
警告
不要过于激进地减少限制。为即将到来的增量备份保留余地，以避免频繁的配额压力事件。
验证清单
- 新的较大大小值在 HBS3 Time Machine 设置中可见。
- Mac 仍然可以运行 Time Machine 备份而不会出现身份验证或目标错误。
- NAS 存储使用趋势稳定，旧版本在后续周期中按预期清除。
