Software Raid-[0,1,5]学习笔记-

<>And it is expensive. To support RAID 1, you need an additional hard disk for every hard disk worth of data. RAID 1 is also known as disk mirroring.

特征：数据冗余，可靠性强。任何一块硬盘坏掉，不会丢失数据。写入慢，读取快。
容量：任何硬盘容量/2
条件：至少两块硬盘，做为RAID的分区大小必须是几乎相同的.

raidtools-1.00.3:

编写/etc/raidtab :

raiddev /dev/md1
raid-level 1
nr-raid-disks 2
nr-spare-disks 1
persistent-superblock 1
chunk-size 4

device /dev/hda2
raid-disk 0
device /dev/hdb2
raid-disk 1
device /dev/hdc2
spare-disk 0
[root@LFS ~]#mkraid /dev/md1

使用mdadm创建raid-1：
[root@LFS ~]#mdadm --create --verbose /dev/md1 --level=raid1 \
--raid-devices=2 --spare-devices=1 --chunk=4 /dev/hda2 /dev/hdb2 /dev/hdc2

[root@LFS ~]#cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 hdc2[2] hdb2[1] hda2[0]
325440 blocks [2/2] [UU]

unused devices:
[root@LFS ~]#mkreiserfs /dev/md1
[root@LFS ~]#mount -t reiserfs /dev/md1 /mnt/raid1

device /dev/hdc2
spare-disk 0
表示用/dev/hdc2做为spare disk，当hda2或hdb2坏掉时，raid会自动启用/dev/hdc2做为映像.

RAID 5

RAID 5 requires three or more disks. RAID 5 distributes, or 'stripes,' parity information evenly across all the disks. If one disk fails, the data can be reconstructed from the parity data on the remaining disks. RAID does not stop; all data is still available even after a single disk failure. RAID level 5 is the preferred choice in most cases: the performance is good, data integrity is ensured, and only one disk's worth of space is lost to parity data. RAID 5 is also known as disk striping with parity.

特征：采用奇偶效验，可靠性强。只有当两块硬盘坏掉时才会丢失数据。并行读写数据，性能也很高。
容量：任何硬盘容量-1
条件：至少三块硬盘，做为RAID的分区大小必须是几乎相同的。

使用raidtools-1.00.3创建raid-5：

编写/etc/raidtab:

raiddev /dev/md5
raid-level 5
nr-raid-disks 3
nr-spare-disks 0
persistent-superblock 1
chunksize 32

parity-algorithm left-symmetric
device /dev/hda3
raid-disk 0
device /dev/hdb3
raid-disk 1
device /dev/hdc3
raid-disk 2
[root@LFS ~]#mkraid /dev/md5

使用mdadm创建raid-5：
[root@LFS ~]#mdadm --create --verbose /dev/md5 --level=raid5 \
--raid-devices=3 --chunk=32 /dev/hda3 /dev/hdb3 /dev/hdc3
[root@LFS ~]#mkreiserfs /dev/md5
[root@LFS ~]#mount -t reiserfs /dev/md5 /mnt/raid5

parity-algorithm left-symmetric
parity-algorithm表示raid5的奇偶效验的运算法则，可用选择有：
left-symmetric left-asymmetric
right-symmetric right-asymmetric
最好性能的是：left-symmetric

LVM RAID :
LVM的物理卷(PV)能够是标准硬盘分区也能够是RAID设备，因此能够在RAID上使用LVM管理分区。
创建PV：
[root@LFS ~]#pvcreate /dev/md5
Physical volume "/dev/md5" successfully created
创建VG：
[root@LFS ~]#vgcreate raid_lvm /dev/md5
Volume group "raid_lvm" successfully created
创建LV:
[root@LFS ~]#lvcreate -L 300M -n "lv_data" raid_lvm
Logical volume "lv_data" created
创建reiserfs:
[root@LFS ~]#mkreiserfs /dev/raid_lvm/lv_data
[root@LFS ~]#mkdir /mnt/data

文章整理：西部数码--专业提供域名注册、虚拟主机服务
http://www.west263.com
以上信息与文章正文是不可分割的一部分,如果您要转载本文章,请保留以上信息，谢谢!