86 lines
3.7 KiB
Markdown
86 lines
3.7 KiB
Markdown
# no space left on device
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- 有时候节点 NotReady， kubelet 日志报 `no space left on device`。
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- 有时候创建 Pod 失败，`describe pod` 看 event 报 `no space left on device`。
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出现这种错误有很多中可能原因，下面我们来根据现象找对应原因。
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## inotify watch 耗尽
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节点 NotReady，kubelet 启动失败，看 kubelet 日志:
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``` bash
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Jul 18 15:20:58 VM_16_16_centos kubelet[11519]: E0718 15:20:58.280275 11519 raw.go:140] Failed to watch directory "/sys/fs/cgroup/memory/kubepods": inotify_add_watch /sys/fs/cgroup/memory/kubepods/burstable/pod926b7ff4-7bff-11e8-945b-52540048533c/6e85761a30707b43ed874e0140f58839618285fc90717153b3cbe7f91629ef5a: no space left on device
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```
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系统调用 `inotify_add_watch` 失败，提示 `no space left on device`， 这是因为系统上进程 watch 文件目录的总数超出了最大限制，可以修改内核参数调高限制，详细请参考本书 [inotify watch 耗尽](runnig-out-of-inotify-watches.md)
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## cgroup 泄露
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查看当前 cgroup 数量:
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``` bash
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$ cat /proc/cgroups | column -t
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#subsys_name hierarchy num_cgroups enabled
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cpuset 5 29 1
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cpu 7 126 1
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cpuacct 7 126 1
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memory 9 127 1
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devices 4 126 1
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freezer 2 29 1
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net_cls 6 29 1
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blkio 10 126 1
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perf_event 3 29 1
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hugetlb 11 29 1
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pids 8 126 1
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net_prio 6 29 1
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```
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cgroup 子系统目录下面所有每个目录及其子目录都认为是一个独立的 cgroup，所以也可以在文件系统中统计目录数来获取实际 cgroup 数量，通常跟 `/proc/cgroups` 里面看到的应该一致:
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``` bash
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$ find -L /sys/fs/cgroup/memory -type d | wc -l
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127
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```
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当 cgroup 泄露发生时，这里的数量就不是真实的了，低版本内核限制最大 65535 个 cgroup，并且开启 kmem 删除 cgroup 时会泄露，大量创建删除容器后泄露了许多 cgroup，最终总数达到 65535，新建容器创建 cgroup 将会失败，报 `no space left on device`
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详细请参考本书 [排障案例: cgroup 泄露](../../troubleshooting-cases/node/cgroup-leaking)
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## 磁盘被写满
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Pod 启动失败，状态 `CreateContainerError`:
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``` bash
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csi-cephfsplugin-27znb 0/2 CreateContainerError 167 17h
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```
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Pod 事件报错:
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``` bash
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Warning Failed 5m1s (x3397 over 17h) kubelet, ip-10-0-151-35.us-west-2.compute.internal (combined from similar events): Error: container create failed: container_linux.go:336: starting container process caused "process_linux.go:399: container init caused \"rootfs_linux.go:58: mounting \\\"/sys\\\" to rootfs \\\"/var/lib/containers/storage/overlay/051e985771cc69f3f699895a1dada9ef6483e912b46a99e004af7bb4852183eb/merged\\\" at \\\"/var/lib/containers/storage/overlay/051e985771cc69f3f699895a1dada9ef6483e912b46a99e004af7bb4852183eb/merged/sys\\\" caused \\\"no space left on device\\\"\""
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```
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## limits 单位错误
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Pod 事件报错：
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```txt
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Mount Volume.SetUp failed for volume "kube-api-access-j562g" :write /var/lib/kubelet/pods /7c251070
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-cf3c-4180-97a2-647e858f3f2/volumes/kubernetes.io~projected/kube-api-access-j562g/..2023_07_25_07_25_22.573608539/ca.crt: no space left on device
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```
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可能是因为定义 requests 和 limits 时忘了写单位，或单位有误:
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```yaml
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limits:
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memory: 512mi # 应该大写开头，改成 512Mi
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```
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```yaml
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limits:
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memory: 512 # 没有单位默认为字节，太小，应带上单位
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```
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根因：可能是因为内存相关的 volume 都受 memory limit 限制 (projected volume, emptydir 等)。
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