From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Mamedov Subject: Re: mdadm freezes the system Date: Tue, 8 Jun 2010 22:24:34 +0600 Message-ID: <20100608222434.3f0fb637@natsu> References: <20100608145913.187a69ca@natsu> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/Gm3GRtiww4m1Y4osy7yNPh1"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20100608145913.187a69ca@natsu> Sender: linux-raid-owner@vger.kernel.org To: Roman Mamedov Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/Gm3GRtiww4m1Y4osy7yNPh1 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Tue, 8 Jun 2010 14:59:13 +0600 Roman Mamedov wrote: > Today, I have decided to convert a three-member RAID5 into a four-member > RAID6. mdadm segfaulted(!) right after the --grow command, and dmesg had > an error about md being unable to overwrite the /sys/.....stripe_cache_si= ze > file. (As I understand, this is already fixed in the latest kernel). >=20 > The array then started rebuilding as 4-member RAID6 seemingly fine, but > shortly after, the system locked up in the same manner as described above. Interestingly though, when I attempted that reshape in 2.6.34 (complete with the described segfault), the array _instantly_ became a 4-disk RAID6 with a rebuilding spare, and the process was running at about 50 MB/sec. And I was able to then remove that spare and shrink the array back to --level=3D5 and --raid-devices=3D3, instantly too. But when I rebooted to 2.6.35-rc2, the same --grow command I used initially (--level=3D6 --raid-devices=3D4) while did not produce a segfault, failed, = asking for the "backup file" to be specified. And after I added the --backup-file switch, it started a slow "Reshape" process, going at about 6 MBytes per second. (And this too, caused a lockup in a way which I described earlier.) Apparently, there is no way to abort this process now, so I paused it using echo idle > /sys/.....sync_action, and copying data away from the array, to recreate it from scratch. So why the same RAID5 to RAID6 conversion started so differently in these t= wo cases? And is it even possible to reshape RAID5 to RAID6 while simultaneous= ly adding a disk, without overwriting all the other disks' contents (it surely looked like this is what was happening in the first case)? --=20 With respect, Roman --Sig_/Gm3GRtiww4m1Y4osy7yNPh1 Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEARECAAYFAkwObsMACgkQTLKSvz+PZwguywCfT85ml2DDLWkPaDVcRBhvZ0Xu f4kAoJBrJAVSrCKhmGH3/bt3jTJpNeDx =YKBm -----END PGP SIGNATURE----- --Sig_/Gm3GRtiww4m1Y4osy7yNPh1--