报错
创建文件报错
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| No space left on device
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syslog日志错误
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| Directory (ino: 4230742) index full, reach max htree level :2
Large directory feature is not enabled on this filesystem
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背景
- 在data目录下无法创建file-1, 但是可以创建file-2, 通过
df -hT 和 df -hi确认不是磁盘不足、不是inode不足导致 - 经过排查是因为目录下的文件超过了目录文件限制. 但是删除一些文件后，创建file-1还是报错
- 话说重启解决99%的问题，所以我重启发现这是剩余的1%的问题.
出现问题的原因
- ext4自身没有做相关方面的限制
- Linux 2.6.23以后引入的HTree索引做的，2-level HTree索引限定了约10-12 million（百万）
- Linux 4.12后largedir特性开启的话3-level限定了约6 billion（十亿）
https://en.wikipedia.org/wiki/Ext4
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| **Unlimited number of subdirectories**
ext4 does not limit the number of subdirectories in a single directory, except by the inherent size limit of the directory itself. (In ext3 a directory can have at most 32,000 subdirectories.)[17][obsolete source] To allow for larger directories and continued performance, ext4 in Linux 2.6.23 and later turns on HTree indices (a specialized version of a B-tree) by default, which allows directories up to approximately 10–12 million entries to be stored in the 2-level HTree index and 2 GB directory size limit for 4 KiB block size, depending on the filename length. In Linux 4.12 and later the large_dir feature enabled a 3-level HTree and directory sizes over 2 GB, allowing approximately 6 billion entries in a single directory.
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解决方案
tune2fs启用磁盘large_dir
我测试过一次这种方案，当时出现了系统异常
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| tune2fs -O large_dir /dev/mapper/vg_test-lv_home
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重建目录
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| mv data data-bak
mkdir data
find data-bak/ -type f | xargs -I {} -n 1 mv {} data/
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参考连接
http://blog.wafcloud.cn/linux/linux-ext4-reach-max-htree-level2.html