raid実装方式

N4100proでのRAID実装はmdadmで実現されている。
SEAGATE ST31000333AS(1TB)を4台でRAID5を構成した状態での/proc/mdstat、mdadm、vgdisplay -vの実行結果は以下のとおり。

[email protected]:/# cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdd1[3] sdc1[2] sdb1[1] sda1[0]
      1959808 blocks [4/4] [UUUU]

md1 : active raid5 sdd2[0] sda2[3] sdb2[2] sdc2[1]
      2924400000 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>

[email protected]:/# mdadm -D /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Sun Feb 22 21:55:58 2009
     Raid Level : raid1
     Array Size : 1959808 (1914.20 MiB 2006.84 MB)
  Used Dev Size : 1959808 (1914.20 MiB 2006.84 MB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Sun Feb 22 21:57:02 2009
          State : active
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

           UUID : 9673410d:2980ff9b:8a507051:76f7589a
         Events : 0.7

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1
       3       8       49        3      active sync   /dev/sdd1

[email protected]:/var# mdadm -D /dev/md1
/dev/md1:
        Version : 00.90.03
  Creation Time : Sun Jan 25 18:57:51 2009
     Raid Level : raid5
     Array Size : 2924400000 (2788.93 GiB 2994.59 GB)
  Used Dev Size : 974800000 (929.64 GiB 998.20 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Sun Feb 22 22:07:03 2009
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 1a0738f8:15101c1c:e244d66f:928e7c73
         Events : 0.20

    Number   Major   Minor   RaidDevice State
       0       8       50        0      active sync   /dev/sdd2
       1       8       34        1      active sync   /dev/sdc2
       2       8       18        2      active sync   /dev/sdb2
       3       8        2        3      active sync   /dev/sda2

データ領域として使用されるのはmd1。md0はswap

[email protected]:/var# vgdisplay  -v
    Finding all volume groups
    Finding volume group "vg0"
  --- Volume group ---
  VG Name               vg0
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               2.72 TB
  PE Size               2.00 MB
  Total PE              1427929
  Alloc PE / Size       1356544 / 2.59 TB
  Free  PE / Size       71385 / 139.42 GB
  VG UUID               ceBl8T-ChHr-QE3O-QyiJ-V6u2-riw0-9ujlRj

  --- Logical volume ---
  LV Name                /dev/vg0/syslv
  VG Name                vg0
  LV UUID                Uxpc0b-8RxA-VmxW-tmLK-wx3M-jYpL-gdWtED
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.00 GB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     2560
  Block device           253:0

  --- Logical volume ---
  LV Name                /dev/vg0/lv0
  VG Name                vg0
  LV UUID                131NP3-BpQd-BIl8-LsjG-i0ol-fwuY-THx6Ta
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                2.59 TB
  Current LE             1356032
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     2560
  Block device           253:1

  --- Physical volumes ---
  PV Name               /dev/md1
  PV UUID               xHu0Yx-jYa7-SafX-Gxqz-hSAd-oEvj-zJ5y90
  PV Status             allocatable
  Total PE / Free PE    1427929 / 71385

[email protected]:/var# mount
rootfs on / type rootfs (rw)
/dev/root on / type ext2 (rw)
/dev/hda5 on /app type ext2 (rw,noatime)
/dev/hda6 on /logfs type ext3 (rw,noatime,data=ordered)
tmpfs on /tmpfs type tmpfs (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
none on /dev/pts type devpts (rw)
/dev/cloop0 on /lib/modules type ext2 (ro)
/dev/cloop1 on /opt type ext2 (ro)
/dev/cloop2 on /img/www type ext2 (ro)
/dev/cloop3 on /img/bin type ext2 (ro)
/dev/cloop4 on /lib/security type ext2 (ro)
/dev/cloop5 on /usr/share/zoneinfo type ext2 (ro)
/dev/cloop6 on /usr/sbin type ext2 (ro)
sunrpc on /tmpfs/var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
nfsd on /proc/fs/nfsd type nfsd (rw)
/dev/vg0/syslv on /raid0/sys type ext3 (rw,data=ordered)
/dev/vg0/lv0 on /raid0/data type ext3 (rw,noatime,data=ordered)

[email protected]:/# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/md/0                               partition       1959800 15692   -1