Re: old server, new server, same performance

Agree with Thom,

I also had the same problem back then when I was migrate from old servers to new server.

After I vacuum the DB at the new servers the result back to normal.

Rgrds

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-----Original Message-----
From: Thom Brown <thom(at)linux(dot)com>
Date: Fri, 14 May 2010 15:03:26
To: Piotr Legiecki<piotrlg(at)ams(dot)edu(dot)pl>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: [PERFORM] old server, new server, same performance

2010/5/14 Piotr Legiecki <piotrlg(at)ams(dot)edu(dot)pl>

> Hi
>
> I have a situation at my work which I simply don't understand and hope
> that here I can find some explanations.
>
> What is on the scene:
> A - old 'server' PC AMD Athlon64 3000+, 2GB RAM, 1 ATA HDD 150GB, Debian
> etch, postgresql 8.1.19
> B - new server HP DL 360, 12GB RAM, Intel Xeon 8 cores CPU, fast SAS
> (mirrored) HDDs, Debian 64 bit, lenny, backported postgresql 8.1.19
> C - our Windows application based on Postgresql 8.1 (not newer)
>
> and second role actors (for pgAdmin)
> D - my old Windows XP computer, Athlon64 X2 3800+, with 100Mbit ethernet
> E - new laptop with Ubuntu, 1000Mbit ethernet
>
> The goal: migrate postgresql from A to B.
>
> Simple and works fine (using pg_dump, psql -d dbname <bakcup_file).
>
> So what is the problem? My simple 'benchmarks' I have done with pgAdmin
> in spare time.
>
> pgAdmin is the latest 1.8.2 on both D and E.
> Using pgAdmin on my (D) computer I have run SELECT * from some_table;
> and noted the execution time on both A and B servers:
> - on A (the old one) about 120sec
> - on B (the new monster) about 120sec (???)
>
> (yes, there is almost no difference)
>
> On the first test runs the postgresql configs on both servers were the
> same, so I have started to optimize (according to postgresql wiki) the
> postgresql on the new (B) server. The difference with my simple select
> * were close to 0.
>
> So this is my first question. Why postgresql behaves so strangely?
> Why there is no difference in database speed between those two machines?
>
> I thought about hardware problem on B, but:
> hdparm shows 140MB/sec on B and 60MB on A (and buffered reads are 8GB on
> B and 800MB on A)
> bonnie++ on B:
>
>> Version 1.03d ------Sequential Output------ --Sequential Input-
>> --Random-
>> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
>> --Seeks--
>> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
>> /sec %CP
>> malwa 24G 51269 71 49649 10 34974 6 48969 82 147840 13
>> 1150 1
>>
> on A:
>
>> Version 1.03 ------Sequential Output------ --Sequential Input-
>> --Random-
>> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
>> --Seeks--
>> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
>> /sec %CP
>> irys 4G 42961 93 41125 13 14414 3 20262 48 38487 5
>> 167.0 0
>>
>
> Here the difference in writings is not so big (wonder why, the price
> between those machines is huge) but in readings are noticeably better on B.
>
> Ok, those were the tests done using my old Windows PC (D) computer. So I
> have decided to do the same using my new laptop with Ubuntu (E).
> The results were soooo strange that now I am completely confused.
>
> The same SELECT:
> - on A first (fresh) run 30sec, second (and so on) about 11sec (??!)
> - on B first run 80sec, second (and so on) about 80sec also
>
> What is going on here? About 8x faster on slower machine?
>
> One more thing comes to my mind. The A server has iso-8859-2 locale and
> database is set to latin2, the B server has utf8 locale, but database is
> still latin2. Does it matter anyway?
>
> So here I'm stuck and hope for help. Is there any bottleneck? How to
> find it?
>
> Regards
> Piotr
>

Have you compared the PostgreSQL configurations between servers?
(postgresql.conf) And how was it installed? Package or compiled from
scratch?

And has the new DB been VACUUM'd?

Thom