RAID1 synchronisation - howto OR not necessary?

Bill Moran wmoran at
Thu Nov 22 12:56:51 PST 2007

"Jan Catrysse" <J.Catrysse at> wrote:
> Dear subscribers,
> I am currently running a production server:
> FreeBSD 6.2 STABLE
> Onboard Intel ICH8R Raid 1 with 2x SATA300 500GB HDD
> Using ATA for Raid1
> On Windows systems it is an absolute must to do a Raid Synchronisation
> every once and a while to maintain data consistency.

Wow.  Any RAID controller with that requirement is junk.  Where did you
get the information from that you had to synchronize?  Does it say so
in the manual?  Does it actually say "every once and a while" or does it
give a specific schedule.

I suspect that you have wrong information ... but if your information is
correct, I'd get a refund on that RAID controller.

> I am some what disturbed that that kind of command / tool seems not
> available on FreeBSD.

There is not, because such a thing should not be necessary.

> Are there other methods to do the synchronisation?
> 1) Maybe atacontrol detach & atacontrol addspare & atacontrol rebuild?
> 2) Maybe data consistency is always maintained automatically by the
> driver?
> 3) Maybe I have to panic and urgently make backups?

If resyncing your raid on a regular basis is truly a requirement, I'd do
#3 at least, followed by getting my money back.

Bill Moran

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