最近在做rac,在环境检查的时候发现swap空间检查不通过,所以我们第一想到的是对swap进行扩容,那么swap扩容有哪些方法呢?这里主要介绍两种方法,一通过添加额外磁盘,扩展swap分区,二是通过本地多余空间的方式扩展swap分区。
一、现象描述
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
查看内容使用情况:
[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
查看磁盘分区挂在情况:
[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
这里看到swap空间为10.7GB,而我们系统内存时16GB,所以至少要扩展6GB才能达到rac检查的要求
二、swap扩容
1、通过添加磁盘扩容
本系统看到是通过逻辑卷做的swap分区,那么我们可以考虑通过逻辑卷扩展的方式扩容swap分区,如果逻辑卷组空间有富余最好,如果没有富余而我们磁盘添加允许的情况下可以通过添加额外的磁盘来扩展逻辑卷组,进而扩展逻辑卷,再到swap分区。本系统是虚拟机,所以扩展磁盘还是比较方便的,具体操作步骤如下:
查看逻辑卷——>查看逻辑卷组——>逻辑卷组扩展(空间不足的情况下)——>卸载逻辑卷——>逻辑卷扩展——>格式化逻辑卷——>重新挂载
1)查看逻辑卷和逻辑卷组
[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
这里看到swap对应的逻辑卷组还有多余的19G空间,所以我们可以直接扩容swap分区
2)卸载swap分区
[root@rac01 ~]# swapoff /dev/mapper/VolGroup-lv_swap
3)扩展swap逻辑卷
[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分区
[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)重新挂在swap分区
[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分区扩容完毕,但如果我们卷组容量不够的情况下如何扩展呢?首先肯定是扩展卷组,然后再重复上面的步骤。下面将扩展卷组的方法在下面补充
磁盘添加
[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)创建新的物理卷
[root@rac02 ~]# pvcreate /dev/sdc Physical volume "/dev/sdc" successfully created
7)扩展逻辑卷组
[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
这里逻辑卷组扩容完毕,后面可以重复1——5步骤完成swap扩容。
正常数据库扩容后需要执行以下命令才能看到扩容后的磁盘容量:
e2fsck -f /dev/vgtest/vgtest-lv
resize2fs /dev/vgtest/vgtest-lv
2、通过本身磁盘剩余空间扩容
1)创建大的swap文件
dd if=/dev/zero of=/home/swap bs=1024 count=20971520
2)格式化swap空间
/sbin/mkswap /home/swap
3)关闭旧swap
swapoff /dev/mapper/vg_swap
4)开启新swap
/sbin/swapon /home/swap
5)开机挂载
/home/swap swap swap defaults 0 0
###备注:在线添加硬盘并扩展逻辑分区
以root身份运行echo "scsi add-single-device a b c d" > /proc/scsi/scsi a是硬盘所在SCSI控制器号(一般机器就一个SCSI控制器,所以就是0); b是硬盘所在SCSI通道的编号(一般单通道的就是0,多通道的要看是哪个通道了); c是硬盘的SCSI ID号(可以通过具体插入的硬盘插槽来判断); d是硬盘的lun号(默认情况都是0) root@ubuntu:~# cat /proc/scsi/scsi root@ubuntu:~# echo "scsi add-single-device 2 0 11 0" > /proc/scsi/scsi root@ubuntu:~# pvcreate /dev/sdk root@ubuntu:~# vgextend lhvg /dev/sdk root@ubuntu:~# lvextend -l +76790 /dev/mapper/vg-lv_data root@ubuntu:~# resize2fs -p /dev/vg/lv_data
##查看磁盘和卷对应关系
pvscan
lvscan
vgscam