Date: Fri, 24 Apr 2009 21:55:31 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-questions@freebsd.org Subject: Re: Unexpected gmirror behavior: Is this a bug? Message-ID: <gst5g4$6ss$1@ger.gmane.org> In-Reply-To: <22026228.2921240597983327.JavaMail.HALO$@halo> References: <32442523.2901240597865043.JavaMail.HALO$@halo> <22026228.2921240597983327.JavaMail.HALO$@halo>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig7924CD881E36D00D279C6349 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Peter Steele wrote: > We had a somewhat startling scenario occur with gmirror. We have system= s with four drives ad4, ad6, ad8, and ad10, with the OS setup on a mirror= ed slice across all four drives. The ad4 drive failed at one point, due t= o a simple bad connection in its drive bay. While it was offline, the sys= tem was continued to be used for a while and new data was added to the mi= rrored file system.=20 >=20 > We eventually took the box down to deal with ad4, and tried simply pull= ing and reinserting the drive. On reboot we saw that the BIOS detected th= e drive, so that was good. However, when FreeBSD got to the point of star= ting up the GEOM driver, instead of reinserting ad4 into the more current= mirror consisting of ad6/ad8/ad10 and resyncing it with that data, the G= EOM driver assumed ad4 was the "good" mirror and ended up resyncing ad6/a= d8/ad10 with the data from ad4, causing the new files we had added to tho= se drives to be lost.=20 >=20 > This only happens with ad4. If ad6 for example goes offline in the same= way, when it is reinserted it does not become the dominant drive and res= ync its data with the other drives. Rather its data is overwritten with t= he data from the 3 member mirror, as you'd expect.=20 >=20 > So, clearly ad4, the first disk, is treated specially. The question is = this a bug or a feature? Is there anyway to prevent this behavior? This w= ould be a disastrous thing to happen in the field on one of our customer = systems.=20 This definitely looks like a bug. Try asking again on the freebsd-geom@ list. Provide output of "gmirror list". =46rom what you said it looks like you did the procedure safely - you turned off the server, then pulled the drive and reinserted it, then turned it on again, right? --------------enig7924CD881E36D00D279C6349 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAknyGTMACgkQldnAQVacBcjjJACgwbx8jJBiYP6VJbYB1aAJcnaA DzsAniHCD2ViR981VNow8eUaEDKf6tJ4 =zO7H -----END PGP SIGNATURE----- --------------enig7924CD881E36D00D279C6349--
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