In many IT circles, raising the “agent-based or agentless backup” question can get people as fired up as an argument over pizza toppings. Everyone has their favorite and argues for it fiercely. “Nothing belongs on a pizza except cheese!” “A slice isn’t a slice without pepperoni!”
But contrary to what you might have heard, there is no one-size-fits-all answer to the question of whether to go agentless or to use agents in your backup installation. Under certain scenarios, it makes sense to deploy an agent-based backup configuration; in others, agentless is the way to go. Both sides of this argument can be correct, depending on the circumstances. In that sense, this really is like a pizza-topping discussion.
The good news is, KeepItSafe can provide both agent-based and agentless backup installations — and, where it benefits our customers, we even deploy solutions using a combination of both configurations in tandem.
To help you decide which backup configuration makes the most sense for your business, I’m going to walk you through some of the pros and cons of working with agents versus deploying an agentless solution. Before we begin, here’s a brief explanation of what these terms actually mean.
In a backup solution, agents are the always-on background programs (running as a service or daemon), which automatically and at regular intervals package all of a system’s data files into a backup job — either as a single object or a set of objects. The server that the agent is running on is able to authenticate itself and does not require a username and password. If the backup solution is running across multiple production servers, these agents need to be installed on each piece of hardware.
Agentless backup, by contrast, involves the replication of data without the use of a service, daemon or similar process running in the background to enable the automatic backup jobs. Agentless backup also does not require the installation of these background programs (agents) on every server storing the data that needs to be backed up. But unlike agent-based backup, an agentless configuration typically does require the creation of a password-protected user account on each machine.
Below I’ve outlined the primary positives and negatives of working with an agent-based solution for backing up your business data. In the next post, I will do the same for agentless backup installations. Keep in mind, this discussion is specifically for KeepItSafe’s industry-leading online backup solutions — and other platforms will differ.
1. You can perform image-based backups. The big advantage here is that all of the information — all data, apps and even Operating System files — can be collected and backed up in a single backup set. Also, restoring a server in its entirely takes only a few clicks.
2. The agent is scanning or detecting block-level change using resources on the target server and not the backup server or network.
3. You can still do single-file restores with our image-based backup for the typical restore scenario of a single file.
4. Your Recovery Time Objectives (RTOs) for entire servers or systems are easier to meet with image-based, warm-standby features.
1. You will have to manage more software, because you will need agents installed on all production servers where you have data that needs backing up.
2. Reboots are required for installs and agent upgrades, which can result in downtime.
3. The agent will need to be constantly running and checking in with the backup server/repository. This can be a good thing, but it can also drain needed resources if the target server is under-specced or over-allocated with production processes.
4. You cannot install an agent on a storage appliance. This means SAN and NAS devices cannot be protected with agent-based backup. Of course, if your SAN or NAS devices present direct, attached storage to your production servers, this will not affect your backup ability.
As you can see, there will be scenarios where an agent-based backup configuration will be all that your business needs to effectively and reliably back up (and be able to restore) your data.
But if any of the negatives listed here concern you, please read my follow-up post for the pros and cons of working with an agentless backup solution.
Technical Sales Engineer, KeepItSafe
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