Do I need ECC Ram for a little Homeserver with zfs and Raid1(NAS, Nextcloud, jails)

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fvdb42

Hello,
I would like to build a new small home server.
I wonder if I need ecc ram.
I have found that this is a myth.
"
Myth #2 - ECC RAM must be used.

○ All filesystems benefit from ECC RAM and ZFS is no different here.

○ ZFS without ECC RAM is safer then other filesystems with ECC RAM (checksums).
"
But I wanted to ask again just to be sure.
Thank you very much.
Frank
 
Yeah, ZFS helps a bit if you have or starting to have memory corruption. When ZFS says some files are bad you definitely want to stop overwriting one-shot backups and run memory testing.

I am a big proponent of ECC memory. Not so much for the error correction, but for the warning messages that you get when your RAM goes back. If you don't have ECC you can't tell whether you need ECC.

ZFS has little to do with it, but if you run large filesystems (ZFS or not) you probably want ECC.
 
ECC is a good idea for any system that is long running and keeps data in memory for a long time.

The amount of memory these days will make it very likely to have bits flipped. Writing cached data to storage, or reusing it, will then give you problems. Out admin at university showed us the log from a SUN which complained about flipped bits due to ECC. When that thing is running long calculations (VLSI P&R f.e.), it would absolutely suck to have a bit error somewhere along the line. ZFS keeps data in memory for a long time, even compressed. Having bit errors in ARC will make life interesting, and running consumer grade HW for month and expect nothing to go wrong is just asking for this.

The rule of ECC for ZFS comes from an area where uptimes are not measured in days. And where loosing a compute run or messing up your data will cost serious money, compared to the few wampum for ECC over regular memory.
 
The myth is the word must. Your question is need. You do not need ECC and it is not a must have, that is true.

If you are selecting ZFS for data integrity, then it stands to reason you should select ECC, for maintaining that integrity. Otherwise you are gambling that you will not need it, which you won't know until something weird happens. If you're comfortable in that scenario with blaming it on weird FreeBSD or ZFS problems and moving on, then I guess you don't need it.
 
To answer the question, you must ask how much you value your data and system reliability. If both are important, then ECC RAM is mandatory.

There's plenty of empirical evidence to support this stance. For instance, this paper form Google, which starts the list of conclusions with:

"About a third of machines and over 8% of DIMMs in our fleet saw at least one correctable error per year."​

Just one memory error might irretrievably corrupt some data or crash your system.

I don't have ECC memory on my media clients because I don't care enough to do it. I don't have ECC memory in my notebook because it's not supported. It's an imperfect world...
 
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