摘要

• BASIC Command
• LVM
• iSCSI

传统的计算机，其工作的原理都是冯·诺依曼体系：机器里面有一个很大的存储器，用来储存所有的信息，还有一个中央区域，执行简单的计算。我们从存储器的这个地方提取一个数据，又从存储器的另一个地方提取一个数据，把这两个数据送到中央算术单元进行相加，然后把计算结果传送到存储器的另一个地方。这样来看，计算机有一个高效运转的中央处理器，工作十分卖力，速度也很快。

相比之下，整个存储器从头到尾待在一旁，很清闲，就像是一个卡片档案柜，除了偶尔翻找几张卡片，档案柜大多数时间都闲置着。显然，如果有更多的处理器同时工作的话，我们的计算速度就能更快一些。问题是当你使用这个处理器时，可能要用到存储器的某个信息，而同时另一个处理器也需要这个信息，机器就会陷入一片混乱中。出于这些原因，大家普遍认为让很多处理器同时工作是个难题。 — 理查德·费曼. 发现的乐趣 (未读·探索家) (Kindle 位置 470-472).

Command

• lsblk

1
2
3
4
5
6
7
8
9
10
11

NAME                                 MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                                    8:0    0 1000G  0 disk
|-sda1                                 8:1    0  500M  0 part /boot
|-sda2                                 8:2    0 19.5G  0 part
| |-vg_nwtest68-lv_root (dm-0)       253:0    0 47.5G  0 lvm  /
| `-vg_nwtest68-lv_swap (dm-1)       253:1    0    2G  0 lvm  [SWAP]
`-sda3                                 8:3    0  980G  0 part
  |-vg_nwtest68-lv_root (dm-0)       253:0    0 47.5G  0 lvm  /
  |-vg_nwtest68-lv_data (dm-2)     253:2    0  100G  0 lvm  /data
sr0                                   11:0    1  3.6G  0 rom  /media/RHEL-6.8 Server.x86_64

• fdisk

The fdisk command below will print the partition table of all mounted block devices.>>>>> More details <<<<<

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

$ sudo fdisk -l
[root@NW-DD-APP ~]# fdisk -l

Disk /dev/sda: 1073.7 GB, 1073741824000 bytes
255 heads, 63 sectors/track, 130541 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0008ca86

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64        2611    20458496   8e  Linux LVM
/dev/sda3            2611      130541  1027599062+  83  Linux

Disk /dev/mapper/vg_nwtest68-lv_root: 51.0 GB, 51011125248 bytes
255 heads, 63 sectors/track, 6201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/vg_nwtest68-lv_swap: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/vg_nwtest68-lv_data: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

• sfdisk

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

  $ sudo sfdisk -l Disk /dev/sda: 130541 cylinders, 255 heads, 63 sectors/track Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0 Device Boot Start End #cyls #blocks Id System /dev/sda1 * 0+ 63- 64- 512000 83 Linux /dev/sda2 63+ 2610- 2547- 20458496 8e Linux LVM /dev/sda3 2610+ 130540 127931- 1027599062+ 83 Linux /dev/sda4 0 - 0 0 0 Empty Disk /dev/mapper/vg_nwtest68-lv_root: 6201 cylinders, 255 heads, 63 sectors/track Disk /dev/mapper/vg_nwtest68-lv_swap: 261 cylinders, 255 heads, 63 sectors/track Disk /dev/mapper/vg_nwtest68-lv_data: 13054 cylinders, 255 heads, 63 sectors/track

• cfdisk

  1 2 3 4 5 6 7 8 9 10 11 12 13 14

  cfdisk (util-linux-ng 2.17.2) Disk Drive: /dev/sda Size: 1073741824000 bytes, 1073.7 GB Heads: 255 Sectors per Track: 63 Cylinders: 130541 Name Flags Part Type FS Type [Label] Size (MB) ----------------------------------------------------------------------------------------------------------------------------------------------------------- Pri/Log Free Space 1.05 * sda1 Boot Primary Linux ext3 524.29 * sda2 Primary Linux LVM 20949.50 * sda3 Primary Linux 1052261.44 * Pri/Log Free Space 5.55 *

LVM

1
2
3
4
5
6
7
8
9
10
11
12
13
14

  -- create partitions on disk drives (type 8e in fdsik)
  -- create physical volumes from the partitions                 
     --> $ sudo pvcreate /dev/sda1
  -- create the volumes group                                     
     --> $ sudo vgcreate -s 16m vg /dev/sda1
  -- allocate logical volumes from the volume group               
     --> $ sudo lvcreate -l 50g -n mylvm vg
  -- format the logical volumes                                   
     --> $ sudo mkfs -t ext4 /dev/vg/mylvm
  -- mount the logical volumes (also update /etc/fstab as needed)
     --> $ mkdir /mylvm,

then --> $ sudo mount /dev/vg/mylvm /mylvm,
then add --> /dev/vg/mylvm /mylvm ext4 defaults 0 0  to the /etc/fstab

查看

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

cat /etc/fstab
df -T -h  

# 查看卷组信息
vgdisplay

# 查看逻辑卷信息
lvdispaly

# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                              8:0    0  500G  0 disk
├─sda1                           8:1    0  500M  0 part /boot
├─sda2                           8:2    0 19.5G  0 part
│ ├─vg_nwtest68-lv_root (dm-0) 253:0    0   35G  0 lvm  /
│ └─vg_nwtest68-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
├─sda3                           8:3    0   20G  0 part
│ └─vg_nwtest68-lv_root (dm-0) 253:0    0   35G  0 lvm  /
└─sda4                           8:4    0   10G  0 part

卸载

1
2
3
4
5

umount  /home

# 删除逻辑卷，注意：检查目录是否为空

lvremove  /dev/mapper/VolGroup-lv_home     

创建

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

#在卷组 (name:VolGroup) 上创建逻辑卷

lvcreate -L 375GB -n lv_slview VolGroup     

# 格式化新建的逻辑卷
mkfs.ext4 /dev/mapper/VolGroup-lv_slview

# 创建挂载点
mkdir /slview

# 挂载
mount /dev/mapper/VolGroup/lv_slview /slview

# 修改 fstab 重启后自动挂载（风险点）
vi /etc/fstab

# reboot

# fstab 异常处理
mount -o remount rw /.

扩容

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82

fdisk -l

# df -kh
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       35G   23G  9.9G  70% /
tmpfs                 932M  208K  932M   1% /dev/shm
/dev/sda1             477M   41M  411M  10% /boot
/dev/mapper/VolGroup-lv_oradata1
                      2.5G  3.8M  2.4G   1% /oradata1

# pvs
  PV         VG          Fmt  Attr PSize  PFree
  /dev/sda2  VolGroup lvm2 a--u 19.51g    0
  /dev/sda3  VolGroup lvm2 a--u 19.99g    0

# pvcreate /dev/sda4
  Physical volume "/dev/sda4" successfully created

# pvs
  PV         VG          Fmt  Attr PSize  PFree
/dev/sda2  VolGroup lvm2 a--u 19.51g     0
/dev/sda3  VolGroup lvm2 a--u 19.99g     0
/dev/sda4              lvm2 ---- 10.00g 10.00g

# vgdisplay
  --- Volume group ---
  VG Name               VolGroup
  ......
  Act PV                2
  VG Size               39.50 GiB
  PE Size               4.00 MiB
  Total PE              10112
  Alloc PE / Size       10112 / 39.50 GiB
  Free  PE / Size       0 / 0   

# vgextend VolGroup /dev/sda4
  Volume group "VolGroup" successfully extended

# vgdisplay
  --- Volume group ---
  VG Name               VolGroup
  ......
  Act PV                3
  VG Size               49.50 GiB
  PE Size               4.00 MiB
  Total PE              12672
  Alloc PE / Size       10112 / 39.50 GiB
  Free  PE / Size       2560 / 10.00 GiB

# lvextend -L +10GB /dev/mapper/VolGroup-lv_oradata1
Size of logical volume VolGroup/lv_oradata1 changed from 2.50 GiB (640 extents) to 12.50 GiB (3200 extents).
  Logical volume lv_oradata1 successfully resized.

# vgdisplay
  --- Volume group ---
  VG Name               VolGroup
  ......
  Act PV                3
  VG Size               49.50 GiB
  PE Size               4.00 MiB
  Total PE              12672
  Alloc PE / Size       12672 / 49.50 GiB
  Free  PE / Size       0 / 0   

# resize2fs /dev/mapper/VolGroup-lv_oradata1
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/VolGroup-lv_oradata1 is mounted on /oradata1;
on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/mapper/vg_nwtest68-lv_oradata1 to 3276800 (4k) blocks.
The filesystem on /dev/mapper/vg_nwtest68-lv_oradata1 is now 3276800 blocks long.

# df -kh
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       35G   23G  9.9G  70% /
tmpfs                 932M  288K  932M   1% /dev/shm
/dev/sda1             477M   41M  411M  10% /boot
/dev/mapper/VolGroup-lv_oradata1
                       13G  6.3M   12G   1% /oradata1

移除

• How to remove missing PV from VG

1
2
3
4

# vgreduce  --removemissing datavg
  WARNING: Device for PV fPFkBx-lbnG-R6Zo-3kq5-KOLA-U1ou-LdNIMD not found or rejected by a filter.
  Couldn\'t find device with uuid fPFkBx-lbnG-R6Zo-3kq5-KOLA-U1ou-LdNIMD.
  Wrote out consistent volume group datavg.

Tips

SCSI

小型计算机系统接口（SCSI，Small Computer System Interface）是一种用于计算机及其周边设备之间（硬盘、软驱、光驱、打印机、扫描仪等）系统级接口的独立处理器标准。最大部分的应用是在存储设备上（例如硬盘、磁带机）。

iSCSI（Internet Small Computer System Interface，发音为/ˈаɪskʌzi/），Internet小型计算机系统接口，又称为IP-SAN，是一种基于因特网及SCSI-3协议下的存储技术，由IETF提出，并于2003年2月11日成为正式的标准。

1
2
3
4
5
6
7
8
9

# iqn
vi /etc/iscsi/initiatorname.iscsi

# 查找iSCSI目标
$ iscsiadm -m discovery -t st -p <组IP地址>:3260
# 登录
$ iscsiadm -m node -T <完整的目标名称,iqn.xxxxxx> -l -p <组IP>:3260
# 注销
$ iscsiadm -m node -u -T <完整的目标名称>-p <组IP地址>:3260

异常处理

1
2
3
4
5
6
7
8
9
10
11

# df -F ufs -o i
Filesystem             iused   ifree  %iused  Mounted on
/dev/dsk/c0t0d0s0     190397 6443139     3%   /
/dev/dsk/c0t0d0s4     457204  165964    73%   /var
/dev/dsk/c0t1d0s3      43539 6461869     1%   /slview
/dev/dsk/c0t0d0s3      19745 1226591     2%   /oracle
# find /var/spool/clientmqueue/ -exec ls {} + |awk '{print $1}' | wc -l
  866350
# find /var/spool/clientmqueue/ -exec ls {} + |awk '{print $1}' | wc -l^C
# getconf ARG_MAX
1048320

Projects

• go-fastdfs | 一个简单的分布式文件存储，具有高性能，高可靠，免维护等优点，支持断点续传，分块上传，小文件合并，自动同步，自动修复
• Fast directory traversal for Golang
• IPFS The Interplanetary File System | Simply Explained

电子书《Linux Perf Master》

• https://riboseyim.gitbook.io/perf
• https://www.gitbook.com/book/riboseyim/linux-perf-master/details

扩展阅读：性能诊断指南

• Linux 性能诊断：负载评估
• Linux 性能诊断：快速检查单
• Linux 性能诊断：JVM

扩展阅读：How Linux Works

• How Linux Works：The Big Picture
• How Linux Works：BASIC Commands
• How Linux Works：BASIC Commands Extension
• How Linux Works：Device and FileSystem
• How Linux Works：Boots
• How Linux Works：用户空间
• How Linux Works：内存管理
• How Linux Works：网络管理
• PreviewHow Linux Works：路由管理

扩展阅读：动态追踪技术

• 动态追踪技术(一)：DTrace 导论
• 动态追踪技术(二)：strace+gdb 溯源 Nginx 内存溢出异常
• 动态追踪技术(三)：Tracing Your Kernel Function!
• 动态追踪技术(四)：基于 Linux bcc/BPF 实现 Go 程序动态追踪
• 动态追踪技术(五)：Welcome DTrace for Linux

参考文献

• 10 Useful Commands to Collect System and Hardware Information in Linux
• An introduction to Linux’s EXT4 filesystem
• How to Increase the size of a Linux LVM by adding a new disk
• Unable to add physical volume ‘/dev/hda’ to volume group
• Linux LVM硬盘管理及LVM扩容
• 创建和挂载 Oracle Solaris 文件系统
• iSCSI存储技术全攻略|2007
• exFAT 文件系统指南
• Virtual filesystems in Linux: Why we need them and how they work
• IPFS The Interplanetary File System | Simply Explained