Data lost due to a power failure

[djdwosk97]

Due to reasons a UPS may not be practical for me to have. So I was wondering, what kind of data integrity issues would I likely face (and what would I likely face in an extreme case) if there was a power outage (when the system is in the middle of a scrub -- since I assume that's the most likely time for damage to occur?)? And what if I don't run any scrubs (since the data is mostly media I likely wouldn't notice bitrot anyway)?

My server is mainly used for media storage (so nothing super critical) and streaming via Plex. I run (or will run) scrubs and SMART tests weekly (that sums up the majority of the non-streaming usage AFAIK).

 

[BigDave]

You basically have less than 1TB of storage that has any redundancy at all
This setup tells me the phrase "may not be practical" is your way of talking yourself
out of spending money on protection of your investment. Just talking from a hardware
standpoint here, you have several hundred dollars worth of server grade equipment.
Let us not forget about the UPS providing good clean power for the stuff you've already
purchased with your hard earned money. You seem to be saying that the total loss of
your data is no big deal. I gotta call bullshit on that!!!

 

[djdwosk97]

You basically have less than 1TB of storage that has any redundancy at all
This setup tells me the phrase "may not be practical" is your way of talking yourself
out of spending money on protection of your investment. Just talking from a hardware
standpoint here, you have several hundred dollars worth of server grade equipment.
Let us not forget about the UPS providing good clean power for the stuff you've already
purchased with your hard earned money. You seem to be saying that the total loss of
your data is no big deal. I gotta call bullshit on that!!!

Well, the UPS would be in a somewhat poorly ventilated room, so the idea of a potential fire hazard trumps potential data loss by quite a bit. And it's really not a money issue, I don't mind spending the <$100~ it would cost for a good UPS. But because of where the server has to be a UPS isn't all that practical unfortunately.

And I never said I wouldn't be pissed if I lost data -- I can accept losing a movie every now and then, but I would be very upset if I lost everything on the server.

 

[BigDave]

Are you saying that the room your server is in, is too warm for the average UPS
to operate with it's environmental specs for temp extremes?
Or are you not trusting UPS because of some of the horror stories you've heard?

 

[djdwosk97]

Are you saying that the room your server is in, is too warm for the average UPS
to operate with it's environmental specs for temp extremes?
Or are you not trusting UPS because of some of the horror stories you've heard?

The latter.

And yes I know, they're horror stories that happened because of some ridiculous set of circumstances that would basically be impossible to repeat.

 

[BigDave]

Down my way, we call the position you are in
"between a rock, and a hard place".

I will say though, now that I think about it, your chance of having a power failure
take out your data is much more likely, than having a quality UPS catch fire.

 

[djdwosk97]

Down my way, we call the position you are in
"between a rock, and a hard place".

I will say though, now that I think about it, your chance of having a power failure
take out your data is much more likely, than having a quality UPS catch fire.

Yes, but one is also significantly worse.

Anyway, I'd be looking at getting an APC BE750G (unless there is some compelling reason why I shouldn't).

 

[jde]

what kind of data integrity issues would I likely face (and what would I likely face in an extreme case)

Could range anywhere from no data loss to a complete loss of a pool. My understanding is that if the power loss occurs in the middle of a write of metadata to the pool, that the pool may be lost.

 

[jde]

The max environmental temperature of the UPS you mentioned is 40C. If the room is so poorly ventilated as to exceed this temperature, you may also be at risk of premature disk failure due to excessive temperatures. The community recommends not running disks at over 40C.

 

[Mr_N]

yeah if your room is poorly ventilated i would be more worried about the PC/HDD's than a UPS you haven't got yet...

 

[jgreco]

There isn't really any circumstance where a simple power-off should actually cause permanent fatal damage to a pool, but power loss events are often not "clean off". Usually a tree falls on the feeder, and causes a brownout, eventually tripping the autorecloser, which shuts off the power for a moment before re-energizing the circuit, which is still shorted because the tree's still on the lines, so you get this very messy, dirty sequence of events where there's brownouts, power losses, power coming back along with all the associated inrush draws cause a second brownout and power spikes, etc. The potential here is really that your PC doesn't generate sufficiently high quality power from the crap your outlet is handing it, and then this causes some problems within the server itself.

The UPS cleans most of that up.

It's much more likely that a properly sized high quality power supply will not suffer from these sorts of concerns. If you're following the Proper Power Supply Sizing sticky recommendations, for example, you're much more likely to have a good result than if you have an undersized power supply that's struggling to start all your hard drives after a power loss and is then hit by a brownout on top of it.

 

[djdwosk97]

There isn't really any circumstance where a simple power-off should actually cause permanent fatal damage to a pool, but power loss events are often not "clean off". Usually a tree falls on the feeder, and causes a brownout, eventually tripping the autorecloser, which shuts off the power for a moment before re-energizing the circuit, which is still shorted because the tree's still on the lines, so you get this very messy, dirty sequence of events where there's brownouts, power losses, power coming back along with all the associated inrush draws cause a second brownout and power spikes, etc. The potential here is really that your PC doesn't generate sufficiently high quality power from the crap your outlet is handing it, and then this causes some problems within the server itself.

The UPS cleans most of that up.

It's much more likely that a properly sized high quality power supply will not suffer from these sorts of concerns. If you're following the Proper Power Supply Sizing sticky recommendations, for example, you're much more likely to have a good result than if you have an undersized power supply that's struggling to start all your hard drives after a power loss and is then hit by a brownout on top of it.

Wouldn't a high end plug strip regulate power surges as well (I don't mean one of those cheap $5 ones)?

As for the PSU, I have a CX500m, so it's definitely large enough and while it's not the best psu in the world, it should still be more than capable of handling a power surge.

 

[jgreco]

No. Power strips do not regulate the normal kind of line crap I'm talking about. They're usually built out of a trio of MOV's that clip voltages that are significantly higher than acceptable. Basically mostly protecting against lightning strikes. I'm talking about actually conditioning the line. There are products that will actually do this without the battery backup side, which are things like the APC LE1200.