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Re: XFS/Postgres/Fragmentation

To: "Benito A. Venegas" <bvenegas@xxxxxxxxxxxxxx>
Subject: Re: XFS/Postgres/Fragmentation
From: Net Llama! <netllama@xxxxxxxxxxxxx>
Date: Tue, 2 Nov 2004 10:54:59 -0500 (EST)
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <Pine.LNX.4.44.0410312120010.1786-100000@xxxxxxxxxxxxxxxxxxxxx>
References: <Pine.LNX.4.44.0410312120010.1786-100000@xxxxxxxxxxxxxxxxxxxxx>
Sender: linux-xfs-bounce@xxxxxxxxxxx
On Sun, 31 Oct 2004, Benito A. Venegas wrote:

> Hi people,
>
> Thanks to everybody for your great effort day by day to maintain this
> great project...
>
> Now..my problem.. :(
>
> I'm experiencing some high fragmentations in one of my boxes, running
> postgresql database.
>
> Last Friday/Saturday I ran some extra maintenance to my postgres DB
> (reindexing, analyze, vacuum full, etc.) due suddenly we started to have
> very slow performance in our queries. This maintenance helped, but later
> I ran xfs_db -r <partition> -c "frag -f" and the
> fragmentation was still high (close to 90%) and xfs_fsr reduced it to 7%
> after to complete 10 loops for all my file systems in /etc/mtab.
>
> Today in the evening I took some statistics and fragmentations level was
> 64% !! :(
>
> #xfs_db -r /dev/sdc1 -c "frag -f"
> actual 2531, ideal 906, fragmentation factor 64.20%
>
>
> Basic info:
>
> -kernel 2.4.19 + xfs 1.2 + some extra patches
> -postgres 7.2.3-1PGDG
>
> #xfs_info /proj
>
> meta-data=/proj                  isize=256    agcount=34, agsize=262144
> blks
> data     =                       bsize=4096   blocks=8885945, imaxpct=25
>          =                       sunit=0      swidth=0 blks, unwritten=0
> naming   =version 2              bsize=4096
> log      =internal               bsize=4096   blocks=1200 version=1
>          =                       sunit=0 blks
> realtime =none                   extsz=65536  blocks=0, rtextents=0
>
> -HW level
>  PE2650 PIII 1400 Mhz Dual CPU, 1Gb ram,
>  /proj is in RAID1 using Perc3/Di (Yes, I know this is a bad raid card,
>   but IMHO this is not causing the fragmentations)
>  Only postgres and a small mysql DB are using this partition.

I provided my xfs_info and uname in a separate email.  However, here's the
xfs_db output:
 xfs_db -r /dev/sda3 -c "frag -f"
actual 249616, ideal 247369, fragmentation factor 0.90%

as you can see, i've got virtully no fragmentation at all.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lonni J Friedman                                netllama@xxxxxxxxxxxxx
Linux Step-by-step & TyGeMo                  http://netllama.ipfox.com


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