this post was submitted on 04 Jul 2023
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How Important is ECC Memory? (self.selfhosted)
submitted 1 year ago by freedomenjoyer to c/[email protected]
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Hello fellow selfhoster, I was wondering how important it is to have ECC Memory. I want a server that is really reliable and ECC memory pops up as one of the must haves for reliability. But it seems to me in my research that it is quite expensive to get a setup with ECC memory. How important is ECC memory for a server (I rely on).

So far I have been rocking a Raspberry pi 4 which has ECC memory

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[–] [email protected] 3 points 1 year ago

From the link:

@PriorProjectEnglish7

The answers in this thread are surprisingly complex, and though they contain true technical facts, their conclusions are generally wrong in terms of what it takes to maintain file integrity. The simple answer is that ECC ram in a networked file server can only protect against memory corruption in the filesystem, but memory corruption can also occur in application code and that’s enough to corrupt a file even if the file server faithfully records the broken bytestream produced by the app.

If you run a Postgres container, and the non-ecc DB process bitflips a key or value, the ECC networked filesystem will faithfully record that corrupted key or value. If the DB bitflips a critical metadata structure in the db file-format, the db file will get corrupted even though the ECC networked filesystem recorded those corrupt bits faithfully and even though the filesystem metadata is intact.
If you run a video transcoding container and it experiences bitflips, that can result in visual glitches or in the video metadata being invalid… again even if the networked filesystem records those corrupt bits faithfully and the filesystem metadata is fully intact.

ECC in the file server prevents complete filesystem loss due to corruption of key FS metadata structures (or at least memory bit-flips… but modern checksumming fs’s like ZFS protect against bit-flips in the storage pretty well). And it protects from individual file loss due to bitflips in the file server. It does NOT protect from the app container corrupting the stream of bytes written to an individual file, which is opaque to the filesystem but which is nonetheless structured data that can be corrupted by the app. If you want ECC-levels of integrity you need to run ECC at all points in the pipeline that are writing data.

That said, I’ve never run an ECC box in my homelab, have never knowingly experienced corruption due to bit flips, and have never knowingly had a file corruption that mattered despite storing and using many terabytes of data. If I care enough about integrity to care about ECC, I probably also care enough to run multiple pipelines on independent hardware and cross-check their results. It’s not something I would lose sleep over.