Today I’m going to share some pointers I learned from my previous experiences in buying and setting up a UPS for a midsize server room. I hope it will be useful to you.
1. Count your sockets
It might seem like a no-brainer, but it is important to ensure that you have sufficient sockets available at the back of your UPS to meet your requirements. The number of sockets that is required can add up quickly once you factor in Internet-access equipment such as routers, modems, firewalls, and VPN appliances. Double that if you are running a multi-homed configuration, or have servers equipped with dual power supply units that are capable of hot failover. Do remember to plug in your monitors and KVMs — if you are using them — into a protected power outlet, too. (Just power them off when not in use) Another solution might be to buy standard power strips and manually rewire their default connectors with plugs that can fit those on your UPS. This is useful for protecting multiple minor pieces of equipment, such as modems and other low-drain equipment.
2. Consider additional UPS units
Some mid-range UPS models offer the ability to “cascade” additional battery packs from the main UPS. The additional battery packs are usually rack-mountable as well and represent a convenient way to increase the runtime of your UPS beyond the default configuration.
An advantage of going this route is that you get to share your available battery runtime more efficiently across all of your equipment. Other potential benefits – though it varies with models — is the lower cost compared to scaling up to a higher range of UPS, as well as the possibility of hot-replacements of batteries.
On the other hand, you have to consider that certain mid-range UPS models do offer a number of features such as the ability to stagger power-on times, as well as giving you the ability to remotely power-cycle equipment at the power receptacle level. Having two separate UPS units working at 40% load does represent a full backup complement.
3. Beware the deep end
If you are working with rack-mounted equipment, you will do well to ensure that your UPS has sufficient space on the back portion after mounting onto your rack. While a 19-inch UPS will fit just fine into a 19-inch rack, the fact is that not all 19-inch racks are built the same.
Smaller racks built to a reduced footprint or inferior racks might not have enough spare leeway for you to plug in the power connectors and still be able to close the back door.
In addition, it is also worth noting that higher-end UPSs typically use customized or non-standard plugs on the UPS-end. It will be wise not to position your rack too far away from the wall power socket.
4. Create a separate power circuit or branch
If you have access to an electrician, it is normally best to have him or her create a separate branch circuit from your office’s (or building’s) main power switchboard. This will help reduce instances of staff tripping your server room’s power by plugging in a faulty microwave oven.
5. Configure for (and test) the shutdown of servers
Many people forget that UPSs are meant only as a temporary measure for intermittent power outages. In an extended blackout or brownout, you do need to shut down your servers to prevent data loss. There are a few ways to do it — including the installation of vendor-specific software utilities — though we’re not going to cover this today.
6. Other points to consider
TechRepublic members suggested a number of useful pointers in my previous article, “Selecting and installing your first UPS.”
TR member Ethical_Loner suggested the online tool on APC’s Web site here to get a better idea of your power requirements. TR member robo_dev cautioned against assuming all the connectors on a UPS are the same. Specifically, watch out for UPSs with power outlets that are divided into “Battery backup” and “Surge suppression”, making sure to plug your equipment into the right outlet.
A topic which I completely missed out on would be the three categories of UPS that are available: off-line, line-interactive, and double-conversion. In a nutshell, it makes sense to go for a double-conversion UPS if budget allows. Due to the presence of a rectifier directly driving the inverter, a sort of electrical “firewall” is formed to better protect against noisy or poor power environment. An off-line UPS will only kick in during a power outage, and a line-interactive lies somewhere in between.
A number of TR members mentioned certain personally favored brands of UPS. Boon or bane, perhaps you can share your experiences with specific brands and models with us.