On Tue, Dec 7, 2010 at 1:35 PM, Ted Ts'o <tytso@xxxxxxx> wrote: > On Tue, Dec 07, 2010 at 01:22:43PM -0500, Mike Snitzer wrote: >> > 1. create a database (from bash): >> > >> > createdb test >> > >> > 2. place the following contents in a file (I used 't.sql'): >> > >> > begin; >> > create temporary table foo as select x as a, ARRAY[x] as b FROM >> > generate_series(1, 10000000 ) AS x; >> > create index foo_a_idx on foo (a); >> > create index foo_b_idx on foo USING GIN (b); >> > rollback; >> > >> > 3. execute that sql: >> > >> > psql -f t.sql --echo-all test >> > >> > With 2.6.34.7 I can re-run [3] all day long, as many times as I want, >> > without issue. >> > >> > With 2.6.37-rc4-13 (the currently-installed KOTD kernel) if tails >> > pretty frequently. > > So I just tried to reproduce this on an Ubuntu 10.04 system running > 2.6.37-rc5 (completely stock except for a few apparmor patches that I > needed to keep the apparmor userspace from complaining). ÂI'm using > Postgres 8.4.5-0ubuntu10.04. > > Using the above procedure, I wasn't able to reproduce. ÂThen I > realized this might have been because I was using an SSD root file > system (which is secured using LUKS/dm-crypt, with LVM on top of > dm-crypt). ÂSo I mounted a file system on a 5400 rpm SSD disk, which > is also protected using LUKS/dm-crypt with LVM on top. ÂI then > executed the PostgresQL commands: > > CREATE TABLESPACE test LOCATION '/kbuild/postgres'; > SET default_tablespace = test; > COMMIT > \quit > > I then re-ran the above proceduing, and verified that all of the I/O > was going to the 5400rpm laptop disk. > > I then ran the above procedure a half-dozen times, and I still haven't > been able to reproduce any Postgresql errors or kernel errors. > > Jon, can you help me identify what might be different with your run > and mine? ÂWhat version of Postgres are you using? I am using postgres 8.4.5 on openSUSE 11.3 x86_64. The problems were observed on both "real" hardware (thinkpad T61p) and in virtualbox, where all current testing is taking place. The current kernel is a "vanilla" (unpatched) kernel. I *did* set wal_sync_method to fdatasync, however, if that is relevant. Otherwise, the pg config is stock. With no crypt involved, I did have to iterate the tests to observe the issue - a half-dozen times or more were necessary. Typically, when crypt was involved, the issue would manifest much more rapidly. -- Jon -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
