SSDs and Power Loss Protection

[Essence_of_War]

On a desktop, without a UPS, is this a feature that it is worth paying a little extra for?

Also, is there a good reference for a list of SSDs that do, and do not have PLP? The only one I can recall seeing with it off-hand is the Crucial m500.

 

[F1shF4t]

The only consumer SSDs I know which do have power loss protection are the crucial m500 and intel 320 (which is now outdated).

I did get a m500 for my external usb3 data drive for that reason. No idea if it is worth it tho as I've never seen any tests which show how effective the PLP is on it.

 

[Elixer]

If you are in a area that has frequent power issues, then buy a UPS.
It will save all your equipment hooked up to it...

 

[Essence_of_War]

I don't have frequent power issues, I'm just a little...anxious or paranoid, I guess?

My desktop isn't even always on either, it spends at least 3/4 of the day powered fully 'off'.

 

[Elixer]

I don't see how it is worse for a SSD than a HD.
They both will lose data if you lose power while it is trying to write something.

That is why I say, save your $$$ and just get a UPS instead of looking to save only part of your system from a power outage.
To be fair, a UPS also protects you from spikes and brownouts as well, which is worse than a power outage.

 

[Mark R]

The problem has been shown in one (now quite old) study to be worse in the vast majority of SSDs when compared with HDD, including a number of consumer level SSDs with integral "power loss protection".

With HDDs, in the event of power loss, the results tend to be fairly consistent; the data in the hard drive's write cache is lost. In general, the cache behaves correctly, and write barrier signals from OS work correctly, to ensure that filesystem crash recovery algorithms can recover the filesystem and prevent catastrophic corruption. There are a few hard drive models that don't correctly process write barriers, and file system corruption can occur. However, most modern OSs have a list of these hard drives and will switch to a safe mode if such a drive is detected.

With SSDs, testing has shown almost all SSDs have a chance of going crazy in the event of power loss when busy. Virtually none correctly handled write barriers, many caused severe file system corruption, and some SSDs were left unresponsive until secure erased, and some were totally bricked by power loss. Even many drives with power loss protection rarely correctly handled write barriers and lost pending writes resulting in minor file system corruption.

 

[Essence_of_War]

So what I'm getting is that if I'm sufficiently paranoid to consider getting an SSD with power loss protection, my money/time/paranoia would be better spent investing in a UPS?

 

[Cerb]

I don't see how it is worse for a SSD than a HD.
They both will lose data if you lose power while it is trying to write something.

HDDs only very rarely write out new mapping data, typically only a handful of times over their healthy lives. SSDs must do it all the time. Big difference. The risk is massive corruption and/or bricking having a greater chance than with an SSD should not be discounted.

Now, I would expect, by now, for most new SSDs to treat batches of writing to OP space in a transaction-safe manner, so that unmapped blocks written to prior to an unexpected power-off could just be cleared and reprogrammed. That alone would save from problems where the PC fails while not writing data to the flash during that time, but with new mapping data having not yet been written (probably the most common problematic reboot, since SSDs so far outpace light users, and any intelligent user is going to avoid using the PC if they expect a power loss risk at the time, such as during a major storm). If it fails while writing, though...

UPSes fail. They do not always fail with warnings. I recently encountered just this event, expecting the UPS to handle being moved from one outlet to another, without affecting the PC it was attached to. The battery was bad, but it holds voltage under no load, so it took using it to find out. And, really, outside of server rooms, how often does anybody perform scheduled failure testing?

Also, what if the PC crashes, or another component goes bad, leaving the SSD hanging around, not getting the next pieces of data it was expecting?

I'd pay a little more for it, and choose one with it v. not, but I wouldn't pay an exorbitant amount more for it. Ironically, ATM, the M500 is one of the cheapest memory-company SSDs to be found, at higher capacities (I was about to do a, "I'd pay X for v. Y not," but it doesn't work out, right now ).

So what I'm getting is that if I'm sufficiently paranoid to consider getting an SSD with power loss protection, my money/time/paranoia would be better spent investing in a UPS?

Either way, if it's a meaningful concern to you, the UPS should come first, and be regularly tested. Just like your backups, batteries aren't any good to if you don't keep up with them.

 

[lucky9]

At least a Standby UPS should be part of every computer system.