Re: What is difference between zfs and ufs?

The greatest dangers to liberty lurk in insidious encroachment by men of
zeal, well-meaning but without understanding.   -- Justice Louis D. Brandeis

On Mon, Aug 17, 2026 at 12:39 PM Wojciech Puchar <[email protected]> wrote:

> >> The only case that you may lose lot of data is that your disk fail
> completely and is not mirrored or in other RAID protection.
> >
> >
> > Unless something has changed fairly recently, to my knowledge UFS does
> not have any explicit mechanism for combating silent data corruption.  This
> is different to ZFS, which, unless you disable it, explicitly does.
> SATA/SAS interface have checksums. Disk drives store data with error
> correcting codes.
>
> Why add useless feature that just generates CPU load and memory traffic.
>
> I have never heard about "silent data corruption" you described to be real
> problem anywhere. hardware does protect from it very well.
>
> This ZFS feature like many others is nothing more than marketing.
> By the way i've personally seen ZFS total failures with completely intact
> disks
>

CERN tested this using high end server hardware. They setup a server to
write data with known checksums. After running it in loop for week, they
found 3000 silent data corruption errors. ZFS was built because SUN had
seen these types of errors. At the volumes that CERN uses these data errors
do exist.

The fact that you have never heard of doesn’t mean that it doesn’t exist.
It means that you have never heard of it. Lack of experience for a single
individual (or small group ) is rarely conclusive. SUN likely has much more
experience with disk errors than you and your colleagues, so I’d suggest
that you research the issue outside of your immediate environment.
You might read the spec sheets on your drives and look for the uncorrected
error rate. For most drives it is 1 TB to 10 TB. Meaning that on long
running reads and reads, the drive will return errors. If you have never
seen it, then either you don’t operate on a scale where is happens enough
to notice and/or the silent errors are happening and your system doesn’t
detect them (which is pretty standard on many other file systems).

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