2021-05-12 14:32:11
Linux擴充套件Swap分割區詳解
2020-06-16 16:51:37
最近在做rac，在環境檢查的時候發現swap空間檢查不通過，所以我們第一想到的是對swap進行擴容，那麼swap擴容有哪些方法呢？這裡主要介紹兩種方法，一通過新增額外磁碟，擴充套件swap分割區，二是通過本地多餘空間的方式擴充套件swap分割區。
一、現象描述
Check: Swap space
Node Name Available Required Status
------------ ------------------------ ------------------------ ----------
rac02 10GB (1.0485756E7KB) 15.7037GB (1.6466544E7KB) failed
rac01 10GB (1.0485756E7KB) 15.7032GB (1.6466E7KB) failed
檢視內容使用情況：
[root@rac01 ~]# free -g
total used free shared buffers cached
Mem: 15 8 7 0 0 8
-/+ buffers/cache: 0 15
Swap: 9 0 9
檢視磁碟分割區掛在情況：
[root@rac01 ~]# cat /etc/fstab
/dev/mapper/VolGroup-lv_root / ext4 defaults 1 1
UUID=ea4095fa-f040-1234-b0b5-abcd1532d332 /boot ext4 defaults 1 2
/dev/mapper/VolGroup-lv_swap swap swap defaults 0 0
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/shm /tmp tmpfs defaults 0 0
[root@rac01 ~]# fdisk -l /dev/mapper/VolGroup-lv_swap
Disk /dev/mapper/VolGroup-lv_swap: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 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
這裡看到swap空間為10.7GB，而我們系統記憶體時16GB，所以至少要擴充套件6GB才能達到rac檢查的要求
二、swap擴容
1、通過新增磁碟擴容
本系統看到是通過邏輯卷做的swap分割區，那麼我們可以考慮通過邏輯捲擴充套件的方式擴容swap分割區，如果邏輯卷組空間有富餘最好，如果沒有富餘而我們磁碟新增允許的情況下可以通過新增額外的磁碟來擴充套件邏輯卷組，進而擴充套件邏輯卷，再到swap分割區。本系統是虛擬機器，所以擴充套件磁碟還是比較方便的，具體操作步驟如下：
檢視邏輯卷——>檢視邏輯卷組——>邏輯卷組擴充套件(空間不足的情況下)——>解除安裝邏輯卷——>邏輯捲擴充套件——>格式化邏輯卷——>重新掛載
1）檢視邏輯卷和邏輯卷組
[root@rac01 ~]# lvdisplay /dev/VolGroup/lv_swap
--- Logical volume ---
LV Path /dev/VolGroup/lv_swap
LV Name lv_swap
VG Name VolGroup
LV UUID 4K2GGg-An39-9Vim-RdQW-U0es-BU9R-gwKoBb
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2017-10-11 14:42:02 +0800
LV Status available
# open 1
LV Size 10.00 GiB
Current LE 2560
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
[root@rac01 ~]# vgdisplay VolGroup
--- Volume group ---
VG Name VolGroup
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 49.51 GiB
PE Size 4.00 MiB
Total PE 12674
Alloc PE / Size 7680 / 30.00 GiB
Free PE / Size 4994 / 19.51 GiB
VG UUID HYL3bE-tccs-SUil-i75E-qUqG-d6dD-6jzj2u
這裡看到swap對應的邏輯卷組還有多餘的19G空間，所以我們可以直接擴容swap分割區
2）解除安裝swap分割區
[root@rac01 ~]# swapoff /dev/mapper/VolGroup-lv_swap
3）擴充套件swap邏輯卷
[root@rac01 ~]# lvextend -L +6GB /dev/mapper/VolGroup-lv_swap
Size of logical volume VolGroup/lv_swap changed from 10.00 GiB (2560 extents) to 16.00 GiB (4096 extents).
Logical volume lv_swap successfully resized.
[root@rac01 ~]# fdisk -l /dev/mapper/VolGroup-lv_swap
Disk /dev/mapper/VolGroup-lv_swap: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 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
4）格式化新swap分割區
[root@rac01 ~]# mkswap /dev/mapper/VolGroup-lv_swap
mkswap: /dev/mapper/VolGroup-lv_swap: warning: don't erase bootbits sectors
on whole disk. Use -f to force.
Setting up swapspace version 1, size = 16777212 KiB
no label, UUID=5cef886d-5537-4aa0-88d8-f4ce92e01698
5）重新掛在swap分割區
[root@rac01 ~]# swapon /dev/mapper/VolGroup-lv_swap
[root@rac01 ~]# free -g
total used free shared buffers cached
Mem: 15 8 7 0 0 8
-/+ buffers/cache: 0 15
Swap: 15 0 15
至此swap分割區擴容完畢，但如果我們捲組容量不夠的情況下如何擴充套件呢？首先肯定是擴充套件卷組，然後再重複上面的步驟。下面將擴充套件卷組的方法在下面補充
磁碟新增
[root@rac02 ~]# fdisk -l |grep sd
Disk /dev/sda: 53.7 GB, 53687091200 bytes
/dev/sda1 * 1 64 512000 83 Linux
/dev/sda2 64 6528 51915776 8e Linux LVM
Disk /dev/sdb: 107.4 GB, 107374182400 bytes
Disk /dev/sdc: 8589 MB, 8589934592 bytes
Disk /dev/sdd: 5368 MB, 5368709120 bytes
/dev/sdd1 1 652 5237158+ 83 Linux
Disk /dev/sdf: 107.4 GB, 107374182400 bytes
/dev/sdf1 1 13054 104856223+ 83 Linux
Disk /dev/sde: 5368 MB, 5368709120 bytes
/dev/sde1 1 652 5237158+ 83 Linux
Disk /dev/sdg: 10.7 GB, 10737418240 bytes
/dev/sdg1 1 1305 10482381 83 Linux
6）建立新的物理卷
[root@rac02 ~]# pvcreate /dev/sdc
Physical volume "/dev/sdc" successfully created
7）擴充套件邏輯卷組
[root@rac02 ~]# vgdisplay
--- Volume group ---
VG Name VolGroup
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 49.51 GiB
PE Size 4.00 MiB
Total PE 12674
Alloc PE / Size 7680 / 30.00 GiB
Free PE / Size 4994 / 19.51 GiB
VG UUID HYL3bE-tccs-SUil-i75E-qUqG-d6dD-6jzj2u
[root@rac02 ~]# vgextend VolGroup /dev/sdc
Volume group "VolGroup" successfully extended
[root@rac02 ~]# vgdisplay
--- Volume group ---
VG Name VolGroup
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 2
Act PV 2
VG Size 57.50 GiB
PE Size 4.00 MiB
Total PE 14721
Alloc PE / Size 7680 / 30.00 GiB
Free PE / Size 7041 / 27.50 GiB
VG UUID HYL3bE-tccs-SUil-i75E-qUqG-d6dD-6jzj2u
這裡邏輯卷組擴容完畢，後面可以重複1——5步驟完成swap擴容。
本文永久更新連結地址：https://www.linuxidc.com/Linux/2018-05/152506.htm
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