Mongodb Backup&restore by using the EC2 Snapshots

LVM Snapshots:

Procedure for creating backups of MongoDB systems using system-level tools, such as LVM or storage appliance, as well as the corresponding restoration strategies.

    These filesystem snapshots, or “block-level” backup methods, use system level tools to create copies of the device that holds MongoDB’s data files. These methods complete quickly and work reliably, but require additional system configuration outside of MongoDB.

     Snapshots work by creating pointers between the live data and a special snapshot volume. After making the snapshot, you mount the snapshot image on your file system and copy data from the snapshot. The resulting backup contains a full copy of all data.

Entire Disk Image

Snapshots create an image of an entire disk image. Unless you need to backup your entire system, consider isolating your MongoDB data files, journal (if applicable), and configuration on one logical disk that doesn’t contain any other data.

Alternately, store all MongoDB data files on a dedicated device so that you can make backups without duplicating extraneous data.

Site Failure Precaution

Ensure that you copy data from snapshots onto other systems. This ensures that data is safe from site failures.

If your mongod instance has journaling enabled, then you can use any kind of file system or volume/block level snapshot tool to create backups.

BackUp and Restore Using LVM on Linux

Create a Snapshot

To create a snapshot with LVM, issue a command as root in the following format:

lvcreate --size 10000M --snapshot --name mdb-snap01 /dev/vg0/mongodb

This command creates an LVM snapshot (with the --snapshot option) named mdb-snap01 of the mongodb volume in the vg0 volume group.

This example creates a snapshot named mdb-snap01 located at /dev/vg0/mdb-snap01.

Ensure that you create snapshots with enough space to account for data growth, particularly for the period of time that it takes to copy data out of the system or to a temporary image.

If your snapshot runs out of space, the snapshot image becomes unusable. Discard this logical volume and create another.

The snapshot will exist when the command returns. You can restore directly from the snapshot at any time or by creating a new logical volume and restoring from this snapshot to the alternate image.

While snapshots are great for creating high quality backups quickly, they are not ideal as a format for storing backup data. Snapshots typically depend and reside on the same storage infrastructure as the original disk images. Therefore, it’s crucial that you archive these snapshots and store them elsewhere.

Restore Directly from a Snapshot

To restore a backup without writing to a compressed gz file, use the following sequence of commands:

umount /dev/vg0/mdb-snap01
lvcreate --size 1G --name mdb-new vg0
dd if=/dev/vg0/mdb-snap01 of=/dev/vg0/mdb-new
mount /dev/vg0/mdb-new /srv/mongodb

The above sequence does the following:

• Creates a new logical volume named mdb-new, in the /dev/vg0 volume group. The path to the new device will be /dev/vg0/mdb-new.
• Mounts the mdb-new disk image to the /srv/mongodb directory. Modify the mount point to correspond to your MongoDB data file location, or other location as needed.

NOTE

The restored snapshot will have a stale mongod.lock file. If you do not remove this file from the snapshot, and MongoDB may assume that the stale lock file indicates an unclean shutdown. If you’re running with storage.journal.enabled enabled, and you do not use db.fsyncLock(), you do not need to remove the mongod.lock file. If you use db.fsyncLock() you will need to remove the lock.