Do i need UPS?

[John Doe]

I have read Cyberjock's "ZFS Storage Design and other FreeNAS information" PowerPoint slide and stumbled over the following entry on page 35:

Code:

The resultant improper shutdowns of your system can result in a corrupted zpool that will no longer mount.

Now i am curious.
Let's assume i do have a power loss and no UPS, how likely is then a corrupted zpool?
Is this guaranteed, will a power loss definitely result in a corrupted zpool or is there only a small chance of corruption?
And if the latter is the case, what is required for that?

Does this only happen in an event, when data is written on the zpool or can this also happen when the NAS is just online?
I will use my FreeNAS only for home user cases, thus i won't have intensive write tasks all the time, and a loss of power is very rare at my location, do i still need an UPS?
Especially if i can read most of the data back from backups.

 

[Cicatrize]

I'd say it's unlikely, but definitely possible. I personally wouldn't risk it. The worst I experienced when I didn't have a UPS was FreeNAS wouldn't boot anymore, and I had to start over, but the pool was fine. It's not worth it, though, unless you don't care about your data. You can get UPSs pretty cheap nowadays.

 

[melloa]

The use of UPS, ECC, Server grade hardware, etc, are best practices from lessons learned. Can you build a NAS without them? Yes. Will your data be safe? No. I use UPS for all my computers, routers, and switches at home. You will need to assess your risk and decide what's best in your case.

 

[John Doe]

The use of UPS, ECC, Server grade hardware, etc, are best practices from lessons learned. Can you build a NAS without them? Yes. Will your data be safe? No. I use UPS for all my computers, routers, and switches at home. You will need to assess your risk and decide what's best in your case.

Well, ECC and a servermainboard is okay, and ECC makes a lot of sense with ZFS, but the other things?
Where does it stop?
If i choose an UPS, doesn't then i also need a redunant power supply?
An UPS without redunant power supply is pretty usless, don't you think so?
Because the power supply could fail.
But redunant server grade power supplies are pretty noisy and loud, because they come with a 40 mm fan, instead of a 120 mm fand typical ATX power supplies do have.

 

[Cicatrize]

Well, ECC and a servermainboard is okay, and ECC makes a lot of sense with ZFS, but the other things?
Where does it stop?
If i choose an UPS, doesn't then i also need a redunant power supply?
An UPS without redunant power supply is pretty usless, don't you think so?
Because the power supply could fail.
But redunant server grade power supplies are pretty noisy and loud, because they come with a 40 mm fan, instead of a 120 mm fand typical ATX power supplies do have.

I don't know if I'd say "useless", but yes, a PSU is another point of possible failure. However, a PSU failure is much less likely than a power outage. Where it stops is essentially how important your data is to you, and how often you back up your data. If you have a sufficient backup solution, I'd still recommend an UPS, but definitely not a redundant PSU, unless you're in a production environment for a business.

I know people here try to push a lot of things on people, and most of it is for good reason, but sometimes, people just might not care about their data enough to get all this stuff. The problem is when they come back after going cheap and saying "my important data is gone, help me!"

 

[melloa]

Well, ECC and a servermainboard is okay, and ECC makes a lot of sense with ZFS, but the other things?

The reality is that one can run a system, FreeNAS included, on anything, as long is comfortable with the risks. No one is trying to impose anything, just provide recommendations.

You can run on a Pentium desktop with 8 GB Ram, one disk for data and 1 USB for boot.

 

[Glorious1]

I've been running over two years without a UPS. I would guess there have been short-term power outages or I have stupidly turned off the main breaker without thinking perhaps 15 or 20 times. Never had any trouble starting back up or any corruption. Of course, now that I've put it in writing, next time will be the charm

 

[Stux]

UPSs also protect from brown outs.

Anyway you don't need a UPS, but any important computer equipment (not just FreeNAS) should be on one.

 

[gpsguy]

If your power goes out during the night, all those UPS' beeping will alert you to the power failure.

Fortuntely, we only have a power failure a couple of times a year.

Anyway you don't need a UPS, but any important computer equipment (not just FreeNAS) should be on one.

 

[melloa]

For a home setup, where most of the data is static, it is OK not to have an UPS, but I got to agree with @Stux. I have four UPSs in my home: 1 for each FreeNAS, one for the router/switch, and one for my desktop.