R1Soft Hot Copy vs LVM2

Courtesy:  R1Soft

Hot Copy (hcp) – Universal Disk Snapshots for Linux

R1Soft Hot Copy (hcp) is the answer to taking online point-in-time disk and volume snapshots in Linux.  Use the hcp command line utility to take an instant snapshot of any mounted file system on almost any block device!

Windows administrators use Volume Shadow Copy Service (VSS).  On Linux servers before Hot Copy nothing equivalent existed.  R1Soft created Hot Copy so every Linux server has a universal disk snapshot that is fast and easy to use.

Why Hot Copy is the Answer to Linux Disk and Volume Snapshots

  • Works on any server-based file system or block device
  • Install without rebooting
  • Eliminates LVM pre-requisite
  • Requires no pre-allocation or pre-configuration of storage
  • Uses existing free space on your disk to maintain snapshots
  • Outstanding performance compared to LVM snapshots
  • Works on most High-Availability and Shared Storage
  • Specialized performance awareness for: Ext2, Ext3, Ext4, and Reiserfs3
  • Snapshots are readable and writable
  • Keep multiple snapshots of each disk or volume

What you Can Do With Hot Copy

  • Add point-in-time open file backups to your existing backup scripts for free e.g. tar and rsync
  • Check your disk for errors with fsck without rebooting and without unmounting your file system!
  • Test scripts and programs in an instant snapshot of your live environment before you use them on real data
  • Keep instantly recoverable snapshots available by taking periodic snapshots via cron


R1Soft Hot Copy can:

  • Create online disk snapshots while a Linux computer is running.
  • Take snapshots so that the computer’s file system is in a consistent state.
  • Use a copy-on-write snapshot method to efficiently grow snapshot storage as changes are made.
  • Create writable and read-only snapshots.
  • Work without dedicated snapshot storage using unused portions of the computers disk to store changed disk blocks.
  • Can create multiple snapshot versions of each block device

R1Soft Hot Copy is implemented as Linux block device driver and is distributed as a loadable kernel module and command line utility (hcp). Hot Copy filters reads and writes to the real disk and performs a copy-on-write when changes are made to the disk. Unused areas of the hard disk are used to store changed blocks in order to maintain a point-in-time snapshot.

Compared to LVM Snaphots

R1Soft Hot Copy has several differences when compared to Logical Volume Manager snapshots:[4]

  • In order to use LVM the computer’s file system must be located on an LVM Volume Group. Many Linux computers do not use LVM. Hot Copy can work with any Linux block device.
  • LVM requires dedicated physical snapshot storage for changed blocks.This requires that the server administrator configure LVM when the system is set up in a way that reserves special storage for LVM snapshots.

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