On Mon, Jun 17, 2013 at 10:23 AM, Matheus de Oliveira <matioli.matheus@xxxxxxxxx> wrote: > > On Mon, Jun 17, 2013 at 12:18 PM, Lonni J Friedman <netllama@xxxxxxxxx> > wrote: >> >> On Sat, Jun 15, 2013 at 8:03 PM, Bruce Momjian <bruce@xxxxxxxxxx> wrote: >> > On Fri, Jun 14, 2013 at 02:29:24PM -0700, Lonni J Friedman wrote: >> >> Greetings, >> >> I'm in the early stages of preparing to upgrade a production 9.2 >> >> cluster to 9.3, by testing the beta of 9.3. All of my testing is >> >> happening on RHEL6-x86_64 on a dedicated server with 128GB RAM and 2x >> >> Intel Xeon E5-2670 CPUs, with all of $PGDATA residing on an 8 disk >> >> RAID10 array. >> >> >> >> Currently, a full pg_basebackup of my data is approaching 800GB in >> >> size (uncompressed), so this isn't a tiny, trivial database. >> >> >> >> I was curious about how much of a performance gain I'd get from >> >> upgrading with the new -j option to pg_upgrade, so first I performed >> >> the upgrade without it to get a baseline. The command I ran for the >> >> upgrade is as follows: >> >> time pg_upgrade -v -d /var/lib/pgsql/9.2/data -D >> >> /var/lib/pgsql/9.3/data -b /usr/pgsql-9.2/bin -B /usr/pgsql-9.3/bin >> >> >> >> time reported the following afterward the upgrade had completed >> >> successfully: >> >> real 24m59.255s >> >> user 0m17.069s >> >> sys 15m25.153s >> >> >> >> >> >> I then repeated the upgrade (after blowing away $PGDATA, and running >> >> initdb again for 9.3), and re-ran pg_upgrade with the same command as >> >> above, only with '-j4' appended to the end. Surprisingly, the >> >> completion time was less than 30 seconds faster. I repeated a third >> >> time with '-j8', and that was about the same completion time as with >> >> '-j4'. I guess I could repeat with 'j2', but I'd be surprised if it >> >> was dramatically faster when -j4 was only marginally so. It seems >> >> like the parallelism of the -j option doesn't seem to be helping much >> >> at all, in my case. >> >> >> >> Is this expected, or is it possible that there's a bug somewhere? Let >> >> me know if I can provide any logs from the upgrade. >> > >> > The documentation states: >> > >> > The <option>--jobs</> option allows multiple CPU cores to be used >> > for copying/linking of files and to dump and reload database >> > schemas >> > in parallel; a good place to start is the maximum of the number of >> > CPU cores and tablespaces. This option can dramatically reduce the >> > time to upgrade a multi-database server running on a multiprocessor >> > machine. >> > >> > My guess is that you didn't have many tablespaces or databases, or the >> > copy time overwhelmed the performance improvement of the parallelism. >> > I am not surprised you didn't see a big win. Can you test --link >> > mode? >> >> I only have 1 tablespace, although I have 9 databases. However, one >> of the databases is about 95% of the total on-disk space, so that's >> probably the explanation of why -j isn't helping me? >> > > That is probably why you DID had some improvement, although so little. > >> >> I don't have sufficient disk space to efficiently test --link mode, >> unless there's some way to quickly roll back to the pre-upgrade >> version of the database after a --link mode upgrade has completed >> successfully that I'm not seeing? >> > > I didn't got it. AFAIK, in link mode it would take **less** space than > normal mode, not the opposite. Am I wrong? No, you're correct, but I want to keep the old version unchanged after the upgrade. I didn't think that was possible with link mode. > > Unless you want to keep a backup of the old cluster on the same machine, but > even on that case you could take this backup compressed, although the > overall time would be worst. -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
