>
> > Just put a note in the installation docs that the place where the 
>database
> > is initialised to should be on a non-Reiser, non-XFS mount...
>
>Sure, we can do that now.

I still think this is not necessarily the right approach either. One
major purpose of using a journaling fs is for fast boot up time after
crash.  If you have a 100 GB database you may wish to have the data
on XFS.  I do think that the WAL log should be on a separate disk and
on a non-journaling fs for performance.

Best Regards,
Carl Garland

_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com


Fri, 04 May 2001 00:58:27 -0400
"carl garland" <carlhgarland@hotmail.com>
Re: Re: New Linux xfs/reiser file systems
Here is a radical idea...

What is it that is causing Postgres trouble? It is the file system's attempts
to maintain some integrity. So I proposed a simple "dbfs" sort of thing which
was the most basic sort of file system possible.

I'm not sure, but I think we can test this hypothesis on the FAT32 file system
on Linux. As far as I know, FAT32 (FAT in general) is a very simple file system
and does very little during operation, except read and write the files and
manage what's been allocated. Plus, the allocation table is very simple in
comparison all the other file systems.

Would pgbench run on a system using ext2, Reiser, then FAT32 be sufficient to
get a feeling for the type of performance Postgres would get, or am I just off
the wall?

If this idea has some merit, what would be the best way to test it? Move the
pg_xlog directory first, then try base? What's the best methodology to try?


carl garland wrote:
> 
> >
> > > Just put a note in the installation docs that the place where the
> >database
> > > is initialised to should be on a non-Reiser, non-XFS mount...
> >
> >Sure, we can do that now.
> 
> I still think this is not necessarily the right approach either. One
> major purpose of using a journaling fs is for fast boot up time after
> crash.  If you have a 100 GB database you may wish to have the data
> on XFS.  I do think that the WAL log should be on a separate disk and
> on a non-journaling fs for performance.
> 
> Best Regards,
> Carl Garland
> 
> _________________________________________________________________
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------------------------
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Fri, 04 May 2001 06:43:06 -0400
mlw <markw@mohawksoft.com>
Re: New Linux xfs/reiser file systems
Before we get too involved in speculating, shouldn't we actually measure the
performance of 7.1 on XFS and Reiserfs?  Since it's easy to disable fsync,
we can test whether that's the problem.  I don't think that logging file
systems must intrinsically give bad performance on fsync since they only log
metadata changes.

I don't have a machine with XFS installed and it will be at least a week
before I could get around to a build.  Any volunteers?

Ken Hirsch



Fri, 4 May 2001 08:24:52 -0400
"Ken Hirsch" <kenhirsch@myself.com>
Re: New Linux xfs/reiser file systems
[ Charset ISO-8859-1 unsupported, converting... ]
> Before we get too involved in speculating, shouldn't we actually measure the
> performance of 7.1 on XFS and Reiserfs?  Since it's easy to disable fsync,
> we can test whether that's the problem.  I don't think that logging file
> systems must intrinsically give bad performance on fsync since they only log
> metadata changes.
> 
> I don't have a machine with XFS installed and it will be at least a week
> before I could get around to a build.  Any volunteers?

There have been multiple reports of poor PostgreSQL performance on
Reiser and xfs.  I don't have numbers, though.  Frankly, I think we need
xfs and reiser experts involved to figure out our options here.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Fri, 4 May 2001 12:36:23 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Re: New Linux xfs/reiser file systems
> > Before we get too involved in speculating, shouldn't we actually measure
the
> > performance of 7.1 on XFS and Reiserfs?  Since it's easy to disable
fsync,
> > we can test whether that's the problem.  I don't think that logging file
> > systems must intrinsically give bad performance on fsync since they only
log
> > metadata changes.
> >
> > I don't have a machine with XFS installed and it will be at least a week
> > before I could get around to a build.  Any volunteers?
>
> There have been multiple reports of poor PostgreSQL performance on
> Reiser and xfs.  I don't have numbers, though.  Frankly, I think we need
> xfs and reiser experts involved to figure out our options here.

I've done some testing to see how Reiserfs performs
vs ext2, and also various for various values of wal_sync_method while on a
reiserfs partition. The attached graph shows the results. The y axis is
transactions per second and the x axis is the transaction number. It was
clear that, at least for my specific app, ext2 was significantly faster.

The hardware I tested on has an Athalon 1 Ghz cpu and 512 MB ram. The
harddrive is a 2 year old IDE drive. I'm running Red Hat 7 with all the
latest updates, and a freshly compiled 2.4.2 kernel with the latest Reiserfs
patch, and of course PostgreSQL 7.1. The transactions were run in a loop,
700 times per test, to insert sample data into 4 tables. I used a PHP script
running on the same machine to do the inserts.

I'd be happy to provide more detail or try a different variation if anyone
is interested.

- Joe
Fri, 4 May 2001 11:07:01 -0700
"Joe Conway" <joe@conway-family.com>
Re: Re: New Linux xfs/reiser file systems
"Ken Hirsch" <kenhirsch@myself.com> writes:

> I don't have a machine with XFS installed and it will be at least a week
> before I could get around to a build.  Any volunteers?

I think I could do that... any useful benchmarks to run?

-- 
Trond Eivind Glomsrï¿½d
Red Hat, Inc.

04 May 2001 14:22:39 -0400
teg@redhat.com (Trond Eivind =?iso-8859-1?q?Glomsr=F8d?=)
Re: Re: New Linux xfs/reiser file systems
> > There have been multiple reports of poor PostgreSQL performance on
> > Reiser and xfs.  I don't have numbers, though.  Frankly, I think we need
> > xfs and reiser experts involved to figure out our options here.
> 
> I've done some testing to see how Reiserfs performs
> vs ext2, and also various for various values of wal_sync_method while on a
> reiserfs partition. The attached graph shows the results. The y axis is
> transactions per second and the x axis is the transaction number. It was
> clear that, at least for my specific app, ext2 was significantly faster.
> 
> The hardware I tested on has an Athalon 1 Ghz cpu and 512 MB ram. The
> harddrive is a 2 year old IDE drive. I'm running Red Hat 7 with all the
> latest updates, and a freshly compiled 2.4.2 kernel with the latest Reiserfs
> patch, and of course PostgreSQL 7.1. The transactions were run in a loop,
> 700 times per test, to insert sample data into 4 tables. I used a PHP script
> running on the same machine to do the inserts.
> 
> I'd be happy to provide more detail or try a different variation if anyone
> is interested.

This is hugely helpful.

Yikes, look at those lines.  It shows a few things.  

First, under Reiser, nosync, fsync, and fdatasync are pretty much the
same.  The big surprise here is that fsync doesn't seem to have any
effect.

Second surprise is that open fsync, which synces on every write rather
than on end of transaction, was slower.  I believe this should be slower
if multiple WAL writes are being made in one transaction.  fdatasync
would sync just at end of transaction, while each WAL write would be
synced by open fsync.

And the largest surpise is that ext2 is faster, but not because of
fsync, and almost double so.  Keep in mind that WAL writes are no the
only write happening.  Though in 7.1 we don't flush the data blocks to
disk, we do write to disk as the buffer cache fill up with dirty
buffers.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Fri, 4 May 2001 14:28:17 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Re: New Linux xfs/reiser file systems
Joe Conway <joe@conway-family.com> wrote:
>
> I've done some testing to see how Reiserfs performs
> vs ext2, and also various for various values of wal_sync_method while on a
> reiserfs partition. The attached graph shows the results. The y axis is
> transactions per second and the x axis is the transaction number. It was
> clear that, at least for my specific app, ext2 was significantly faster.

This is great, thanks a lot!  Among other things it tells us, it appears
that fsync() is not the problem on Reiserfs.  I don't know the details of
Reiserfs, but I think a lot of work has gone into optimizing it for very
small files, so you can use the file system as a simple database for
strings, a la Windows registry.  I don't remember hearing about optimizing
for large files and large block reads and writes.

XFS, on the other hand, is used for very large files on SGI systems.

I think the XFS and Reiserfs folks will be happy to look at the performance
problem, but it would be very helpful for them to have a prepackaged
benchmark (or two or three) to use.   We should set up an FTP area to share
them.  Joe, can you contribute yours?   Does anybody else have anything?

Already, Trond Eivind Glomsrï¿½d teg@redhat.com has volunteered to test on
XFS.  The easier we make it, the more help we'll get.

Ken Hirsch






Fri, 4 May 2001 15:58:07 -0400
"Ken Hirsch" <kahirsch@bellsouth.net>
Re: Re: New Linux xfs/reiser file systems
> I think the XFS and Reiserfs folks will be happy to look at the
performance
> problem, but it would be very helpful for them to have a prepackaged
> benchmark (or two or three) to use.   We should set up an FTP area to
share
> them.  Joe, can you contribute yours?   Does anybody else have anything?
>

I don't mind contributing the script and schema that I used, but one thing I
failed to mention in my first post is that the first thing the script does
is open connections to 256 databases (all on this same machine), and the
transactions are relatively evenly dispersed among the 256 connections. The
test was originally written to try out an idea to allow scalability by
partitioning the data into seperate databases (which could eventually each
live on its own server). If you are interested I can modify the test to use
only one database and rerun the same tests this weekend.

Joe


Fri, 4 May 2001 14:13:47 -0700
"Joe Conway" <joe@conway-family.com>
Re: Re: New Linux xfs/reiser file systems
teg@redhat.com (Trond Eivind Glomsrï¿½d) writes:

> "Ken Hirsch" <kenhirsch@myself.com> writes:
> 
> > I don't have a machine with XFS installed and it will be at least a week
> > before I could get around to a build.  Any volunteers?
> 
> I think I could do that... any useful benchmarks to run?

In lack of bigger benchmarks, I tried postgresql 7.1 on a Red Hat
Linux 7.1 system with the SGI XFS modifications. The differences were
very small.








-- 
Trond Eivind Glomsrï¿½d
Red Hat, Inc.
07 May 2001 18:07:16 -0400
teg@redhat.com (Trond Eivind =?iso-8859-1?q?Glomsr=F8d?=)
Re: Re: New Linux xfs/reiser file systems
> teg@redhat.com (Trond Eivind Glomsr?d) writes:
> 
> > "Ken Hirsch" <kenhirsch@myself.com> writes:
> > 
> > > I don't have a machine with XFS installed and it will be at least a week
> > > before I could get around to a build.  Any volunteers?
> > 
> > I think I could do that... any useful benchmarks to run?
> 
> In lack of bigger benchmarks, I tried postgresql 7.1 on a Red Hat
> Linux 7.1 system with the SGI XFS modifications. The differences were
> very small.
> 

Thanks.  That is very helpful.  Seems XFS is fine.  According to Joe
Conway, reiser has some problems.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Mon, 7 May 2001 19:07:06 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Re: New Linux xfs/reiser file systems
Quoting Trond Eivind Glomsrï¿½d <teg@redhat.com>:

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> 
> > > 
> > > When compared to the earlier ones (including XFS), you'll note that
> ReiserFS
> > > performance is rather poor in some of the tests  - it takes 37 vs. 13
> > > seconds for 8192 inserts, when the inserts are different transactions.
> > 
> > That is all the fsync delay, probably, and it should be using fdatasync()
> > on that kernel.
> 
> And it does seem to work that way with XFS...

I'm concearned about this because we are going to switch our fist server to a
Journaling FS (on Linux).
Searching and asking I found out that for our short term work we need ReiserFS
(it's for a proxy server).
Put the interesting thing was that for large (very large) files, everybody
recomends XFS.
The drawback of XFS is that it's very, very sloooow when deleting files.

Saludos... :-)

-- 
El mejor sistema operativo es aquel que te da de comer.
Cuida tu dieta.
-----------------------------------------------------------------
Martin Marques                  |        mmarques@unl.edu.ar
Programador, Administrador      |       Centro de Telematica
                       Universidad Nacional
                            del Litoral
-----------------------------------------------------------------

Wed,  9 May 2001 14:21:10 +0300
=?iso-8859-1?B?TWFydO1uIE1hcnF16XM=?= <martin@bugs.unl.edu.ar>
Re: Re: New Linux xfs/reiser file systems
Quoting Bruce Momjian <pgman@candle.pha.pa.us>:

> > I'm concearned about this because we are going to switch our
> > fist server to a Journaling FS (on Linux).  Searching and asking
> > I found out that for our short term work we need ReiserFS (it's
> > for a proxy server).  Put the interesting thing was that for
> > large (very large) files, everybody recomends XFS.  The drawback
> > of XFS is that it's very, very sloooow when deleting files.
> 
> Why do all these file systems seem to have one major negative?

In the case of XFS they told me that it was slow deleting, but I guess that they
were trying to tell me that reiser would do the job on a proxy cache better then
XFS.
Everybody put there thumbs-up to XFS when talking about databases (because of
the large file size).

Saludos... :-)

-- 
El mejor sistema operativo es aquel que te da de comer.
Cuida tu dieta.
-----------------------------------------------------------------
Martin Marques                  |        mmarques@unl.edu.ar
Programador, Administrador      |       Centro de Telematica
                       Universidad Nacional
                            del Litoral
-----------------------------------------------------------------

Wed,  9 May 2001 14:30:03 +0300
=?iso-8859-1?B?TWFydO1uIE1hcnF16XM=?= <martin@bugs.unl.edu.ar>
Re: Re: New Linux xfs/reiser file systems
teg@redhat.com (Trond Eivind Glomsrï¿½d) writes:

> teg@redhat.com (Trond Eivind Glomsrï¿½d) writes:
> 
> > "Ken Hirsch" <kenhirsch@myself.com> writes:
> > 
> > > I don't have a machine with XFS installed and it will be at least a week
> > > before I could get around to a build.  Any volunteers?
> > 
> > I think I could do that... any useful benchmarks to run?
> 
> In lack of bigger benchmarks, I tried postgresql 7.1 on a Red Hat
> Linux 7.1 system with the SGI XFS modifications. The differences were
> very small.

And here is the one for ReiserFS - same kernel, but recompiled to turn
off debugging




When compared to the earlier ones (including XFS), you'll note that ReiserFS
performance is rather poor in some of the tests  - it takes 37 vs. 13
seconds for 8192 inserts, when the inserts are different transactions.
-- 
Trond Eivind Glomsrï¿½d
Red Hat, Inc.
09 May 2001 11:16:34 -0400
teg@redhat.com (Trond Eivind =?iso-8859-1?q?Glomsr=F8d?=)
Re: Re: New Linux xfs/reiser file systems
> 
> When compared to the earlier ones (including XFS), you'll note that ReiserFS
> performance is rather poor in some of the tests  - it takes 37 vs. 13
> seconds for 8192 inserts, when the inserts are different transactions.

That is all the fsync delay, probably, and it should be using fdatasync()
on that kernel.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Wed, 9 May 2001 12:14:32 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Re: New Linux xfs/reiser file systems
Bruce Momjian <pgman@candle.pha.pa.us> writes:

> > 
> > When compared to the earlier ones (including XFS), you'll note that ReiserFS
> > performance is rather poor in some of the tests  - it takes 37 vs. 13
> > seconds for 8192 inserts, when the inserts are different transactions.
> 
> That is all the fsync delay, probably, and it should be using fdatasync()
> on that kernel.

And it does seem to work that way with XFS...

-- 
Trond Eivind Glomsrï¿½d
Red Hat, Inc.

09 May 2001 12:15:35 -0400
teg@redhat.com (Trond Eivind =?iso-8859-1?q?Glomsr=F8d?=)
Re: Re: New Linux xfs/reiser file systems
> I'm concearned about this because we are going to switch our
> fist server to a Journaling FS (on Linux).  Searching and asking
> I found out that for our short term work we need ReiserFS (it's
> for a proxy server).  Put the interesting thing was that for
> large (very large) files, everybody recomends XFS.  The drawback
> of XFS is that it's very, very sloooow when deleting files.

Why do all these file systems seem to have one major negative?

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Wed, 9 May 2001 13:24:32 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Re: New Linux xfs/reiser file systems
Makes it more fun :)  Kinda like a lottery ticket:

- reliable (cherry)
- fast (cherry)
- resource hog (lemon)
--
Rod Taylor
   BarChord Entertainment Inc.
----- Original Message -----
From: "Bruce Momjian" <pgman@candle.pha.pa.us>
To: "Martï¿½n Marquï¿½s" <martin@bugs.unl.edu.ar>
Cc: "Trond Eivind Glomsrï¿½d" <teg@redhat.com>;
<pgsql-hackers@postgresql.org>
Sent: Wednesday, May 09, 2001 1:24 PM
Subject: Re: [HACKERS] Re: New Linux xfs/reiser file systems


> > I'm concearned about this because we are going to switch our
> > fist server to a Journaling FS (on Linux).  Searching and asking
> > I found out that for our short term work we need ReiserFS (it's
> > for a proxy server).  Put the interesting thing was that for
> > large (very large) files, everybody recomends XFS.  The drawback
> > of XFS is that it's very, very sloooow when deleting files.
>
> Why do all these file systems seem to have one major negative?
>
> --
>   Bruce Momjian                        |  http://candle.pha.pa.us
>   pgman@candle.pha.pa.us               |  (610) 853-3000
>   +  If your life is a hard drive,     |  830 Blythe Avenue
>   +  Christ can be your backup.        |  Drexel Hill, Pennsylvania
19026
>
> ---------------------------(end of
broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
>


Wed, 9 May 2001 13:59:55 -0400
"Rod Taylor" <rbt@barchord.com>
Re: Re: New Linux xfs/reiser file systems
Hello !
I am forwarding the following from lkml

It seems that the only case when XFS is slow is the 'rm -rf linux' 
[which can be considered as a good sign for linux]. For all other 
operation XFS is the winner.

YAS

<MessageFromLKML>
From: Ricardo Galli (gallir@uib.es)
Date: Wed May 09 2001 - 20:45:46 EDT

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Ricochet works, USB performance sucks."

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 > It would be great to see a table of ReiserFS/XFS/Ext2+index performance
 > results. Well, to make it really fair it should be Ext3+index so I'd
 > better add 'backport the patch to 2.2' or 'bug Stephen and friends to
 > hurry up' to my to-do list.

You can find a simple benchmark (an average of three samples) among reiser,
ext2, xfs and fat32 under Linux:

http://bulma.lug.net/body.phtml?nIdNoticia=626

Although is Spanish, the tables are easy to understand.

The benchmark was carried up by Guillem Cantallops, student of the
University of Balearics Islands and member or the local LUG...

BASIC WORDS ;-)
Escritura: Writing
Lectura: Reading
Borrado: Deletion
Copia: Copy
Extracciï¿½n: Extraction

Regards,

--ricardo
http://m3d.uib.es/~gallir/

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Bruce Momjian wrote:

>>I'm concearned about this because we are going to switch our
>>fist server to a Journaling FS (on Linux).  Searching and asking
>>I found out that for our short term work we need ReiserFS (it's
>>for a proxy server).  Put the interesting thing was that for
>>large (very large) files, everybody recomends XFS.  The drawback
>>of XFS is that it's very, very sloooow when deleting files.
>>
> 
> Why do all these file systems seem to have one major negative?
> 
> --
>   Bruce Momjian                        |  http://candle.pha.pa.us
>   pgman@candle.pha.pa.us               |  (610) 853-3000
>   +  If your life is a hard drive,     |  830 Blythe Avenue
>   +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
> 


Thu, 10 May 2001 10:55:16 +0200
Yaacov Akiba Slama <ya@slamail.org>
Re: New Linux xfs/reiser file systems