We only upgraded to CentOS 4.1 due to an emergency data center migration... We weren't prepared to undergo the risk of a 64-bit upgrade at the same time. I believe we're experimenting with 64-bit kernel now as part of our efforts to diagnose and resolve the I/O issue.
-JF > -----Original Message----- > From: Heikki Tuuri [mailto:[EMAIL PROTECTED] > Sent: Monday, October 17, 2005 10:52 AM > To: mysql@lists.mysql.com > Subject: Re: Non-linear degradation in bulk loads? > > Jon, > > I do not know. Why not install a 64-bit Linux in your computer? > > Regards, > > Heikki > Oracle/Innobase > > ----- Alkuperäinen viesti ----- > Lähettäjä: "Jon Frisby" <[EMAIL PROTECTED]> > Vastaanottaja: "Heikki Tuuri" <[EMAIL PROTECTED]>; > <mysql@lists.mysql.com> > Lähetetty: Monday, October 17, 2005 8:46 PM > Aihe: RE: Non-linear degradation in bulk loads? > > > Actually, I believe we're running 32-bit, with bigmem... > Does similar behavior occur in such a scenario? > > -JF > > > > -----Original Message----- > > From: Heikki Tuuri [mailto:[EMAIL PROTECTED] > > Sent: Sunday, October 16, 2005 2:23 AM > > To: mysql@lists.mysql.com > > Subject: Re: Non-linear degradation in bulk loads? > > > > Jon, > > > > your hardware/OS combination is quite new and unusual. It > might indeed > > be an OS problem. We observed from a 64-bit RHEL > > 4 that when the file cache of the OS grew bigger than 4 GB, > then the > > file I/O performance dropped to one tenth of the normal. > You would not > > expect that kind of behavior from a 64-bit OS. > > > > When you see the slowdown, what does 'top' say about the OS > file cache > > size? > > > > " > > The database is our main sites database but we've > dramatically reduced > > the load on that machine over the past couple months > through careful > > optimization of our code. The box is a dual, dual-core > Opteron, 8GB > > of RAM running a 32-bit Linux 2.4 kernel and MySQL 4.0.20 > (32-bit of > > course). We have 1GB allocated to the buffer pool, and our > usual 1GB > > * > > 3 log files. 8 I/O threads. > > > > Load on the box sits at around 6-7, with a large (>50%) > amount of time > > spent in wait state, but actual disk throughput to our > software RAID > > array (No longer on a SAN...) is quite low -- 6-9k blocks/s > out, 1-6k > > blocks/s in. > > " > > > > Regards, > > > > Heikki > > > > > > ----- Original Message ----- > > From: ""Jon Frisby"" <[EMAIL PROTECTED]> > > Newsgroups: mailing.database.myodbc > > Sent: Friday, October 14, 2005 10:39 PM > > Subject: RE: Non-linear degradation in bulk loads? > > > > > > > I've tried tweaking the structure of the schema to have, > > for example, a = > > > PRIMARY KEY index on email, no other indexes, and then > > insert in sorted = > > > order -- made no improvement whatsoever. Another clue that > > leads me to = > > > believe that this may be an OS issue: Starting a large cp > > on the same = > > > box (from a local filesystem other than the one the InnoDB > > data pool was = > > > on, to NFS) caused MySQL to become COMPLETELY backlogged > > (we went from = > > > ~15-20 connections at any given instant to 750 (our > > max_connections = > > > setting)). > > > > > > -JF > > > > > > > > >> -----Original Message----- > > >> From: Heikki Tuuri [mailto:[EMAIL PROTECTED] > > >> Sent: Wednesday, October 12, 2005 8:15 AM > > >> To: mysql@lists.mysql.com > > >> Subject: Re: Non-linear degradation in bulk loads? > > >>=20 > > >> Jon, > > >>=20 > > >> hmm... maybe one of the indexes inevitably is in a random order. > > >>=20 > > >> Please post a typical > > >>=20 > > >> SHOW INNODB STATUS\G > > >>=20 > > >> when the inserts happen slowly. > > >>=20 > > >> What is your my.cnf like? > > >>=20 > > >> Regards, > > >>=20 > > >> Heikki > > >> Innobase/Oracle > > >>=20 > > >> ----- Alkuper=E4inen viesti ----- > > >> L=E4hett=E4j=E4: "Jon Frisby" <[EMAIL PROTECTED]> > > >> Vastaanottaja: "Heikki Tuuri" <[EMAIL PROTECTED]>;=20 > > >><mysql@lists.mysql.com> > > >> L=E4hetetty: Wednesday, October 12, 2005 3:08 AM > > >> Aihe: RE: Non-linear degradation in bulk loads? > > >>=20 > > >>=20 > > >> > Two solutions: 1) sort the rows to be inserted on the > > key 'email'=20 > > >> > before inserting. > > >> > > > >> > 2) Or: > > >> > > > >> > http://dev.mysql.com/doc/mysql/en/innodb-tuning.html > > >> > " > > >> > If you have UNIQUE constraints on secondary keys, starting=20 > > >> from MySQL > > >> > 3.23.52 and 4.0.3, you can speed up table imports by > > temporarily=20 > > >> > turning off the uniqueness checks during the import session: > > >> > SET UNIQUE_CHECKS=3D0; > > >> > > > >> > For big tables, this saves a lot of disk I/O because > > InnoDB can use=20 > > >> > its insert buffer to write secondary index records in a batch. > > >> > " > > >> > > > >> > But make sure you do not have any duplicates in the rows! > > >>=20 > > >> After sending my mail, I discovered SET > UNIQUE_CHECKS=3D0, and=20 > > >>subsequent to that it also occurred to me to try putting the=20 > > >>data in in sorted order. Unfortunately, doing=20 > UNIQUE_CHECKS=3D0 > > >>did not work, and even the combination of=20 both did not work. > > >>First chunk (3.4m rows) was ~1.5 minutes,=20 second was ~5 > > >>minutes... > > >>=20 > > >> At this point I'm inclined to believe that there is > something=20 > > >>very wrong with the disk subsystem because of this and other=20 > > >>problems (doing a large cp from the datapool filesystem to=20 > > >>another filesystem brought the database to a near-halt, among=20 > > >>other things). > > >>=20 > > >> As a stop-gap solution, I created the table with no indexes,=20 > > >>and loaded all the data (loaded in linear time), and plan on=20 > > >>doing a CREATE UNIQUE INDEX on the table. Will this > happen=20 in > > >>linear time, or near-linear time? > > >>=20 > > >> *sigh* > > >>=20 > > >> -JF=20 > > >>=20 > > >>=20 > > >> -- > > >> MySQL General Mailing List > > >> For list archives: http://lists.mysql.com/mysql > > >> To unsubscribe: =20 > > >> http://lists.mysql.com/[EMAIL PROTECTED] > > >>=20 > > >>=20 > > > > > > -- > > > MySQL General Mailing List > > > For list archives: http://lists.mysql.com/mysql To unsubscribe: > > > > http://lists.mysql.com/[EMAIL PROTECTED] > > > > > > > > > -- > > MySQL General Mailing List > > For list archives: http://lists.mysql.com/mysql To unsubscribe: > > http://lists.mysql.com/[EMAIL PROTECTED] > > > > > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: > http://lists.mysql.com/[EMAIL PROTECTED] > > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
