I have an SME server v9 up and running on a VPS (virtual private server).
The provider makes snapshot based backups daily, weekly and monthly.
You can switch to an alternate snapshot in seconds, which works great for an instant full system restore.
Instead of switching you can also attach a snapshotted volume to the live server as an extra hard disk and use this to restore individual files and folders.
When I try to do this I can see the additional hard disk, but I have no idea how to safely mount it properly and browse its content.
I understand the following commands and have a decent understanding of Centos Linux:
Linux disk utilities df -h fdisk -l sfdisk -l cat /etc/fstab mount mdadm -D /dev/md0 mdadm -D /dev/md1 cat /proc/mdstat Logical Volume Manager (LVM) vgdisplay lvdisplay pvdisplay
The normal output without any extra hard disk attached:
[root@home]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/main-root 19G 6.8G 11G 39% / tmpfs 499M 0 499M 0% /dev/shm /dev/md0 239M 82M 145M 36% /boot
[root@home]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 vda1[0] 255936 blocks super 1.0 [2/1] [U_] md1 : active raid1 vda2[0] 20697984 blocks super 1.1 [2/1] [U_] bitmap: 1/1 pages [4KB], 65536KB chunk
[root@home]# sfdisk -l Disk /dev/vda: 41610 cylinders, 16 heads, 63 sectors/track Units = cylinders of 516096 bytes, blocks of 1024 bytes, counting from 0 Device Boot Start End #cyls #blocks Id System /dev/vda1 * 2+ 509- 508- 256000 fd Linux raid autodetect start: (c,h,s) expected (2,0,33) found (0,32,33) end: (c,h,s) expected (509,15,31) found (31,254,31) /dev/vda2 509+ 41610- 41101- 20714496 fd Linux raid autodetect start: (c,h,s) expected (509,15,32) found (31,254,32) end: (c,h,s) expected (1023,15,63) found (1023,254,63) /dev/vda3 0 - 0 0 0 Empty /dev/vda4 0 - 0 0 0 Empty Disk /dev/md1: 5174496 cylinders, 2 heads, 4 sectors/track Disk /dev/mapper/main-root: 2449 cylinders, 255 heads, 63 sectors/track Disk /dev/mapper/main-swap: 126 cylinders, 255 heads, 63 sectors/track Disk /dev/md0: 63984 cylinders, 2 heads, 4 sectors/track
Devices syntax
/dev/hda,hdb,hdc... (= hard disks) /dev/hda1..99 (= partitions on hard disk hda) /dev/hdb1..99 (= partitions on hard disk hdb) /dev/sda,sdb,sdc... (= removable storage) /dev/sda1,sda2,sda3... (= partitions on removable storage sda) /dev/md0 (md = mirror disk = first RAID1) /dev/md1 (md = mirror disk = second RAID1) /dev/vda (virtual hard disk) /dev/vda1, vda2, vda3, vda4 (partitions on 'vda')
Note that vda1 belongs to md0 and vda2 belongs to md1 but both vda1 and vda2 are part of vda.
The recommended partitioning scheme dictates a separate “/boot” partition to hold the Linux kernel. For most users, a 100 MB boot partition is sufficient. In this case it is 239MB. /dev/mapper/main-root then aliases /dev/md1 as it is 19GB in size and holds the root (“/”) partition (also known as ‘data’ partition.
/dev/mapper/main-root and /dev/mapper/main-swap indicate Logical Volume Manager (LVM) is in use. LVM is used to combine one or more phyisical devices into a logical device.
So for our SME server we have 1 virtual hard disk (vda) with 2 partitions (vda1 and vda2).
vda1 is 239MB and used to hold “/boot” as part of the degraded RAID1 volume md0
vda2 is 19GB and used to hold “/” as part of the degraded RAID1 volume md1
Use “sme noraid nolvm”
When installing SME server on a Virtual Private Server (VPS), it is best not to use RAID or LVM. Install SME server using “sme noraid nolvm”. Note that for the /boot partition the installer will still use a degraded RAID1 volume. The root (“/”) partition however will be a plain physical partition.
If you use the noraid and nolvm options then you will get something like this:
[root@home]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 vda1[0] 255936 blocks super 1.0 [2/1] [U_] unused devices: <none> [root@home]# fdisk -l Disk /dev/vda: 536.9 GB, 536870912000 bytes 16 heads, 63 sectors/track, 1040253 cylinders Units = cylinders of 1008 * 512 = 516096 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00068d1d Device Boot Start End Blocks Id System /dev/vda1 * 3 510 256000 fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/vda2 510 8572 4063232 82 Linux swap / Solaris Partition 2 does not end on cylinder boundary. /dev/vda3 8572 1040254 519967744 83 Linux Partition 3 does not end on cylinder boundary. Disk /dev/md0: 262 MB, 262078464 bytes 2 heads, 4 sectors/track, 63984 cylinders Units = cylinders of 8 * 512 = 4096 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000
/dev/vda3 contains the data and can easily be mounted(!)
Mounting a 2nd SME server partition (only works for NOLVM / NORAID).
mkdir /mnt/zzz mount /dev/vdb3 /mnt/zzz