What Is My Objective?
I remember when I first entered the IT industry, someone mentioned that the industry was full of ‘TLA’s’, where ‘TLA’ in itself was a Three Letter Acronym… talk about play on word. However, looking into it today , I found that this is in fact an Initialism, with the key difference being the ‘pronouncability’ (yeah I don’t think that’s a word) of the abbreviation. Look it up. So TLA is actually an initialism, not a TLA….. who new!
That fun fact of the day also leads me into today’s topic of backup, and the all-important RPO and RTO concepts around backup to Azure.
I’ve talked about Azure backup previously, which comes in two flavours. A straight to Azure Backup version, and a version that uses a server local to the servers and applications you are backing up, before shipping it off to Azure for up to 999 recovery point for up to 99 years!
Let’s talk about the TLA, or, initialism for a bit. RPO is an abbreviation for Recovery Point Objective and RTO is an abbreviation for Recovery Time Objective. What’s the difference? The RPO refers to how often you will perform a backup of the data you want to protect. This often differs per application where you might want a shorter RPO for more important data, and a longer RPO on data that might just contain configuration information that doesn’t change often. This is how the RPO options look for Azure Backup Server ‘as a service’ in the form of a backup policy.
Pretty neat huh!? Backup retention for 10 years and I’ve only used 174 recovery points. As a nice aside, there are some safeties built into Azure backup so that to recover data you need to be able to log into the Azure Backup portal and generate a PIN. You also have the ability to request restoration of deleted backup data in Azure for up to 14 days after deletion incase it has been deleted accidentally or with malicious intent!
Onto RTO. The Recovery Time Objective is the amount of time taken to restore the data you require.
This is where the point made earlier about the local server becomes important. Because Azure Backup is a cloud service and backed up data will in most cases traverse your internet link (encrypted of course!), then larger amounts of data will take longer to restore and have a longer RTO. Having a local server means that the restore will most likely be on a local LAN the servers you are restoring to. If you’re like me, then your LAN is probably 1Gbe or 10Gbe and your Internet link is probably 100Mb/s. Of course, this varies and there are also some caveats (as with anything) such as the retention period and how much space you allocate to the local backup server, and whether you need to restore from off-site ‘long term’ backup. What drives the RTO decision? Usually Service Level Agreements, the cost of local storage and the size of your Internet link.
How fast is Azure backup? Don’t quote me on this but I’ve seen on a standard Azure Backup Server service, throughput of as much as 600Mb/s (that’s mega-bits). So not bad if your Internet link can handle it.
So in summary, RPO’s drive how often you need data protected and RTO’s are the time it takes to get the data back.
If I were to use a breakfast analogy – An RPO would be how often eat breakfast at a cafe and the RTO would be how long it takes me to get back to that cafe. OK – not my best but hopefully you get the idea!