MDADM 陣列限制為 2.0TB

我有一個 MDADM 陣列，在 RAID5 配置中有四個 1TB 磁碟。這是的相關部分mdadm --detail /dev/md1：

       Version : 00.90
    Raid Level : raid5
    Array Size : 2929537920 (2793.83 GiB 2999.85 GB)
 Used Dev Size : 976512640 (931.28 GiB 999.95 GB)
  Raid Devices : 4
 Total Devices : 4
Preferred Minor : 1
   Persistence : Superblock is persistent

它顯示該陣列為 2.8TB。這裡是fdisk -l /dev/md1：

Disk /dev/md1: 2999.8 GB, 2999846830080 bytes
2 heads, 4 sectors/track, 732384480 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 65536 bytes / 196608 bytes
Disk identifier: 0xffffffff
Disk /dev/md1 doesn't contain a valid partition table

fdisk 也顯示它是 3TB。但是，df -Th不同意：

Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/md1      ext3    1.8T  1.8T     0 100% /

為什麼一切都顯示/dev/md1為 3TB，但空間僅限於 2TB？

其他細節：Ubuntu 10.10

更新：

$ tune2fs -l /dev/md1:

tune2fs 1.41.12 (17-May-2010)
Filesystem volume name:   <none>
Last mounted on:          <not available>
Filesystem UUID:          1b4e9420-61ee-4ffd-817a-28831f2aeaf2
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file
Filesystem flags:         signed_directory_hash
Default mount options:    (none)
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              122068992
Block count:              488255968
Reserved block count:     24412798
Free blocks:              69746292
Free inodes:              121882953
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      907
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8192
Inode blocks per group:   512
RAID stride:              16
RAID stripe width:        32
Filesystem created:       Sun Oct 17 01:14:23 2010
Last mount time:          Mon Dec  6 01:24:31 2010
Last write time:          Mon Dec  6 00:45:41 2010
Mount count:              12
Maximum mount count:      23
Last checked:             Sun Dec  5 20:37:35 2010
Check interval:           15552000 (6 months)
Next check after:         Fri Jun  3 21:37:35 2011
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Required extra isize:     28
Desired extra isize:      28
Journal inode:            8
First orphan inode:       55550208
Default directory hash:   half_md4
Directory Hash Seed:      2a386fcb-b24f-4f40-bf4c-7c03489b086c
Journal backup:           inode blocks

您是否在創建文件系統後添加了第 4 個驅動器？這可能導致 FS 小於底層設備。

或者，也許您的 ext3 有 1k 個塊，因為這會導致 2TB 文件系統大小限制（ext3 大小限制）。

請發布“sudo tune2fs -l /dev/md1”的輸出，並仔細查看塊大小行。

引用自：https://serverfault.com/questions/211907