FreeBSD and ECC memory?

[Nejc Škoberne]

Hello,

I am buying hardware for a FreeBSD server and me and my friend argue about
whether or not to by ECC RAM for the server. It is a HP ProLiant ML110 G4
machine and currently it has 2 x 512 HP DDR2 ECC memory.

My friend says buying ECC memory is not wise, because we would not profit from
it since this server will not need very high availability (but still we'd like
to make it a solid server). And also that ECC memory slows down memory
operations by 2-3% all together. Also, we would profit from buying non-ECC
memory because we already have 2 x 1GB non-ECC memory and if we:

  - buy extra 2 x 1GB non-ECC memory we'll have 4GB all together (4 x 1GB)
  - buy extra 2 x 1GB ECC memory we'll have 3GB all together (2 x 512MB + 2 x 1GB)

1. So, what would you base your decision on? Is getting ECC worth losing 1GB of
    non-ECC memory?
2. What are your experiences with ECC?
3. Did self-halt because of a memory error (having ECC memory) ever happen to someone
    here?
4. If there is non-ECC memory installed, how does FreeBSD recognizes (corrects?)
    memory errors?

Thanks,
Nejc