当ZFS无法提供未损坏的数据时,程序会看到什么?

EIO确实是当前ZFS实现的唯一答案。

打开的ZFS“错误”要求以某种方式读取损坏的数据: http://bugs.opensolaris.org/bugdatabase/printableBug.do?bug_id=6186106

看看 http://www.cuddletech.com/blog/pivot/entry.php?id=980

Solaris 10:

# Create a test pool
[root@tesalia z]# cd /tmp
[root@tesalia tmp]# mkfile 100M zz
[root@tesalia tmp]# zpool create prueba /tmp/zz

# Fill the pool
[root@tesalia /]# dd if=/dev/zero of=/prueba/dummy_file
dd: writing to `/prueba/dummy_file': No space left on device
129537+0 records in
129536+0 records out
66322432 bytes (66 MB) copied, 1.6093 s, 41.2 MB/s

# Umount the pool
[root@tesalia /]# zpool export prueba

# Corrupt the pool on purpose
[root@tesalia /]# dd if=/dev/urandom of=/tmp/zz seek=100000 count=1 conv=notrunc
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.0715209 s, 7.2 kB/s

# Mount the pool again
zpool import -d /tmp prueba

# Try to read the corrupted data
[root@tesalia tmp]# md5sum /prueba/dummy_file 
md5sum: /prueba/dummy_file: I/O error

# Read the manual
[root@tesalia tmp]# man -s2 read
[...]
RETURN VALUES
     Upon successful completion,  read()  and  readv()  return  a
     non-negative integer indicating the number of bytes actually
     read. Otherwise, the functions return -1 and  set  errno  to
     indicate the error.

ERRORS
     The read(), readv(), and pread() functions will fail if:
[...]
     EIO        A physical I/O error has occurred, [...]

您必须导出/导入测试池,因为如果不导出,直接覆盖(池损坏)将丢失,因为文件仍将缓存在操作系统内存中。

不,目前ZFS将拒绝向您提供损坏的数据。应该如此。

除了一张支票,你怎么还 EIO 错误来自 read() 在特定于文件系统的低级数据救援实用程序之外是否有意义?