Let’s start by explaining the image above. The blue illustration shows the most efficient way of backing up one full backup, followed by daily infinite incremental backups. The red illustration shows an older strategy (still used by many vendor backup solutions) – a weekly full backup with incremental chains. As you can see, the required storage footprint is more than doubled in the red illustration. An infinite backup strategy is becoming increasingly more popular as organisation strategies and policies are forever changing with future technologies.
To define “Incremental-Forever” aka infinite incremental backups:
The most basic form of incremental backup consists of identifying, recording and preserving only those files that have changed since the last backup. Since changes are typically low, incremental backups are much smaller and quicker than full backups. For instance, following a full backup on Friday a Monday backup will contain only those files that changed since Friday. A Tuesday backup contains only those files that changed since Monday and so on. In addition, the restore process is optimized, as only the latest versions of blocks that belong to a restored backup are restored. Since the same area on the production disk is recovered only one time, the same block is not written to multiple times. Therefore, one full backup followed by many backup increments act as your retention but with lower I/O impact on your storage overall.
In addition to this, Arcserve allows for multilevel incremental schedules on one plan. This means that you are able to add separate weekly, monthly, and yearly schedules to the same job that could consist of incremental or full backups. Unlike the common backup software as shown in the red illustration above, Arcserve’s infinite incremental backup allows the synthetic operation to create a new full backup which is limited to the size of the incremental file instead of the complete size of a full backup file.
So you would see a something similar to below with Arcserve’s infinite backup strategy:
Infinite incremental forever backups may sound crazy. However organizations with very long retention requirements should consider this philosophy.
After a bit of searching on the web for general concerns with infinite or incremental forever backups & from my experience with multiple organizations and setups, the main concern with infinite incremental is that should any one of the copies created fail, including the first (full) backup, the possibility of restoration will be incomplete or impossible from the chain and the longer you go without a new full backup the more risk you take. What if corruption happens along the way and you lose an increment? You would lose the integrity of the chain, up to last working backup.
Looking at the image below, Backup #1 is dependent on the Full backup, Backup #2 is dependent on Backup #1 and so on. If corruption occurred on Backup #2, the last restorable would be backup #1.
With Arcserve this is not the case. Arcserve has a completely different method of holding the restore points. Basically, each increment and backup is a pointing file rather than a reference to a set of block data set in a destination. Arcserve also allows for Verify backup to be run to check reference points and rebuild the chain if needed. This protects your infinite retention chain and preserves data. Verify backup can be run manually or scheduled as a multilevel incremental backup. The image below shows how Arcserve holds this data compared to other backup vendors as seen above.
I ran a lab test on this and deleted an incremental pointer from Arcserve backup destination on a protected server from the middle of its chain. I then immediately tried to restore from the next point forward and received errors. I was able to return to a point before the deleted point but nothing following. I then ran a manual verify backup, and I was able to restore from all points in the chain except the deleted point. Arcserve can thus repair corruption or loss in the chain and statements such as “should any one of the copies created fail, including the first (full) backup, the possibility of restoration will be incomplete” are no longer valid when using Arcserve Unified Data Protection.
Why infinite incremental with Arcserve UDP?
- It reduces backup windows from hours to minutes for many applications, while providing faster recovery of your data.
- In a virtual environment, further data reduction can be observed with incremental changes being feed by CBT change block tracking on a lower block level.
- It can support 24 x 7 backup strategy, reducing your RPO drastically.
- It reduces costs by consolidating backup devices & backup storage across your infrastructure.
- It reduces media costs incurred from offloading to tape cartridges needed on previous backup strategies to fulfill retention requirements that included bloated backups (D2D2T). When infinite incremental is your strategy going forward then retention can be kept on disk and rather replicated offsite to disk once again for peace of mind. This reduces your RTO.
- This will enable full on and off site data retention, compliant with industry standards & corporate data policies.
- Reduce the amount of data that goes across the local area network (LAN) and what’s replicated on across your wide area network (WAN)
- Reduce data growth, as all incremental backups contain only the block level changes since your previous backup (incremental).
- Source side global deduplication on incremental backups, making backups even more efficient and shortening windows: no comparison with the backup target is done since only changed blocks are identified at the source.
Why should Arcserve to be your infinite incremental backup vendor?
Because of the impressive data reduction ratios and costs savings that are achievable. Below is a breakdown of what you can achieve with Arcserve infinite incremental bundled with deduplication and further compression (even more impressive on a virtual environment using change block tracking: more data reduction can be observed).
A traditional infinite incremental backup before compression and deduplication, and no CBT:
A Virtual CBT infinite incremental backup before compression & deduplication:
A de-duplicated infinite incremental backup before compression:
A compressed, de-duplicated infinite incremental:
It’s easy to see who the leader is in backup data reduction in the market, right? Don’t build your infrastructure around your backup software. Let Arcserve reduce your cost, backup windows, RTO, RPOs and maintenance.