如何把一个已有LV 改成条带化

使用RAID卡组RAID0时，初始化时会进行条带化，stripesize设置就是条带化大小。用 *** 作系统组建动态磁盘时，可以组建跨区卷和带区卷，跨区卷是一个包含多块磁盘上的空间的卷（最多32块），向跨区卷中存储数据信息的顺序是存满第一块磁盘再逐渐向后面的磁盘中存储。通过创建跨区卷，我们可以将多块物理磁盘中的空余空间分配成同一个卷，利用了资源。但是，跨区卷并不能提高性能或容错。带区卷是由2个或多个磁盘中的空余空间组成的卷（最多32块磁盘），在向带区卷中写入数据时，数据被分割成固定大小的数据块，然后同时向阵列中的每一块磁盘写入不同的数据块。这个过程显著提高了磁盘效率和性能，但是，带区卷不提供容错性。也就是通常说的软RAID0。主板自带的RAID0功能也是条带化的。

逻辑卷（LVM）它是Linux环境下对磁盘分区进行管理的一种机制，它是建立在物理存储设备之上的一个抽象层，优点在于灵活管理。特点： 1、动在线态扩容 2、离线裁剪 3、数据条带化 4、数据镜像相关特点分析，可以参考黑马程序员社区一个板块都是技术知识。我朋友在黑马学的运维，现在13k16薪。我也正在学习呢。

LVM条带模式：交错存储数据，数据均匀地分布在VG的指定磁盘中，对于I/O密集的应用有良好的效果。

（1）条带化后可以均匀分配II/O压力，从而改善磁盘性能

（2）避免单一磁盘的热点问题

（3）可以是数据分布均匀

[root@localhost ~]# lsblk

sdb 8:16 0 1G 0 disk

sdc 8:32 0 2G 0 disk

sdd 8:48 0 3G 0 disk

sde 8:64 0 4G 0 disk

[root@localhost ~]# pvcreate /dev/sd{b..e}

Physical volume "/dev/sdb" successfully created.

Physical volume "/dev/sdc" successfully created.

Physical volume "/dev/sdd" successfully created.

Physical volume "/dev/sde" successfully created.

[root@localhost ~]# vgcreate datavg /dev/sd{b..e}

Volume group "datavg" successfully created

[root@localhost ~]# lvcreate -L 2G -n lv_data1 -i4 datavg

Using default stripesize 64.00 KiB.

Logical volume "lv_data1" created.

[root@localhost ~]# lvdisplay -m

……..

--- Logical volume ---

LV Path/dev/datavg/lv_data1

LV Namelv_data1

VG Namedatavg

LV UUIDg5gVhI-u0cO-BwOK-7OfU-Jg0w-Gl0B-24KPz7

LV Write Accessread/write

LV Creation host, time localhost.localdomain, 2021-04-23 15:34:46 +0800

LV Status available

# open 0

LV Size2.00 GiB

Current LE 512

Segments 1

Allocation inherit

Read ahead sectors auto

[root@localhost ~]# lvcreate -L 1G -i3 -I 128 -n lv_data2 datavg /dev/sdb /dev/sdc /dev/sdd

Rounding size 1.00 GiB (256 extents) up to stripe boundary size <1.01 GiB(258 extents).

Logical volume "lv_data2" created.

[root@localhost ~]# lvdisplay -m

…………….

--- Logical volume ---

LV Path/dev/datavg/lv_data1

LV Namelv_data1

VG Namedatavg

LV UUIDg5gVhI-u0cO-BwOK-7OfU-Jg0w-Gl0B-24KPz7

LV Write Accessread/write

LV Creation host, time localhost.localdomain, 2021-04-23 15:34:46 +0800

LV Status available

# open 0

LV Size2.00 GiB

Current LE 512

Segments 1

Allocation inherit

Read ahead sectors auto

--- Segments ---

Logical extents 0 to 511:

Typestriped

Stripes 4

Stripe size 64.00 KiB

Stripe 0:

Physical volume /dev/sdb

Physical extents 0 to 127

Stripe 1:

Physical volume /dev/sdc

Physical extents 0 to 127

Stripe 2:

Physical volume /dev/sdd

Physical extents 0 to 127

Stripe 3:

Physical volume /dev/sde

Physical extents 0 to 127

--- Logical volume ---

LV Path/dev/datavg/lv_data2

LV Namelv_data2

VG Namedatavg

LV UUID9LDa2t-u4mi-m8Uv-KZtD-82hl-MUxY-GX6BPy

LV Write Accessread/write

LV Creation host, time localhost.localdomain, 2021-04-23 15:41:24 +0800

LV Status available

# open 0

LV Size<1.01 GiB

Current LE 258

Segments 1

Allocation inherit

Read ahead sectors auto

--- Segments ---

Logical extents 0 to 257:

Typestriped

Stripes 3

Stripe size 128.00 KiB

Stripe 0:

Physical volume /dev/sdb

Physical extents 128 to 213

Stripe 1:

Physical volume /dev/sdc

Physical extents 128 to 213

Stripe 2:

Physical volume /dev/sdd

Physical extents 128 to 213

[root@localhost ~]# dmsetup deps /dev/datavg/lv_data{1,2}

/dev/datavg/lv_data1: 4 dependencies: (8, 64) (8, 48) (8, 32) (8, 16)

/dev/datavg/lv_data2: 3 dependencies: (8, 48) (8, 32) (8, 16)

[root@localhost ~]# mkdir data{1,2}

[root@localhost ~]# mkfs.xfs /dev/datavg/lv_data

lv_data1 lv_data2

[root@localhost ~]# mkfs.xfs /dev/datavg/lv_data1

[root@localhost ~]# mkfs.xfs /dev/datavg/lv_data2

[root@localhost ~]# mount /dev/datavg/lv_data1 data1

[root@localhost ~]# mount /dev/datavg/lv_data2 data2

# dd if=/dev/zero of=/root/data1/1 bs=1M count=1024

# iostat 1

avg-cpu: %user %nice %system %iowait %steal %idle

0.000.00 96.100.000.003.90

Device:tpskB_read/skB_wrtn/skB_readkB_wrtn

sda 0.00 0.00 0.00 0 0

sdb2044.16 0.65138368.83 0 106544

sdc2049.3511.69138327.27 9 106512

sdd2040.26 0.00138306.49 0 106496

sde2048.0511.69138223.38 9 106432

可以看到4块磁盘均有数据同时写入

# dd if=/dev/zero of=/root/data2/2 bs=1M count=1024

# iostat 1

avg-cpu: %user %nice %system %iowait %steal %idle

1.040.00 47.921.040.00 50.00

Device:tpskB_read/skB_wrtn/skB_readkB_wrtn

sda 3.1233.33 0.00 32 0

dm-0 3.1233.33 0.00 32 0

dm-1 0.00 0.00 0.00 0 0

dm-2 0.00 0.00 0.00 0 0

dm-3 0.00 0.00 0.00 0 0

dm-4 0.00 0.00 0.00 0 0

dm-5 0.00 0.00 0.00 0 0

dm-6 0.00 0.00 0.00 0 0

sdb1129.17 9.38144000.00 9 138240

sdc1126.04 0.00144133.33 0 138368

sdd1132.2918.23144000.00 17 138240

sde 0.00 0.00 0.00 0 0

dm-7 0.00 0.00 0.00 0 0

dm-8 3386.4627.60432000.00 26 414720

可以看到3块磁盘均有数据同时写入

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