Date: Thu, 23 Apr 2020 18:57:24 -0400 From: Chris Gordon <freebsd@theory14.net> To: David Christensen <dpchrist@holgerdanske.com> Cc: freebsd-questions@freebsd.org Subject: Re: best upgrade process for server Message-ID: <22A86243-7351-4A2F-8B43-10E80C61901E@theory14.net> In-Reply-To: <618aed37-a64b-9471-4353-366460d057d7@holgerdanske.com> References: <1810714722.149383351.1587616694832.JavaMail.zimbra@shaw.ca> <618aed37-a64b-9471-4353-366460d057d7@holgerdanske.com>
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> On Apr 23, 2020, at 4:25 PM, David Christensen = <dpchrist@holgerdanske.com> wrote: >=20 > When it was time to retire my previous desktop/ Linux SOHO server with = an up-to-date FreeBSD server, I bought a lightly used Dell PowerEdge T30 = with one Xeon E3-1225 v5 processor, one 8 GB ECC memory module, one 1 TB = SATA HDD, and one DVD+/-RW drive. (It is important that computers = running ZFS have ECC memory.) I would clarify the statement about ECC memory in that ECC memory is = important for any system where memory errors are significantly = detrimental to the applications running on the server whereas to justify = the additional cost. =20 As for file systems, ECC memory is no more or less important for ZFS, = UFS, ext*, NTFS, etc. The only case where I think the argument for ZFS = could be stronger than other file systems is by virtue of ZFS typically = using more memory for the ARC and thereby theoretically increasing the = probability of a read serviced from ARC experiencing a bit flip. This = thinking, though, applies to applications, too -- as more memory is = used, the probability of encountering a memory error increases. The = idea that ZFS uniquely "requires" ECC memory to be "safe" often seems to = stem back to an a blog post about the "scrub of death". This has been = debunked many times. Allan Jude discusses this is far more detail and = expertise than I can starting at about minute 57 of Episode 200 of the = BSDNOw podcast: = https://www.jupiterbroadcasting.com/116226/getting-scrubbed-to-death-bsd-n= ow-200/ That said, if you can afford ECC memory, you're better than without it. = You are even better with backups that are on something other than the = machine you're backing up. You're even better if you can periodically = test those backups and validate that they are indeed good and = recoverable. Chris=
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