Told u to use JFS :)
Also, as I tried to explain in my previous mail, the block size of your
disks is
not necessarily 8kb, i.e. you will probably not save any I/O request
that way
(probably make it worse).
A reason to choose a 8kb block for the File System, theoretically, its
because
you want the database to read from same, tracks and cylinders to save
seeks.
However, modern file systems put together blocks when it writes them,
because
if it didn't you would be in serious trouble.
Why? postgresql uses transactions and when one transaction reads and at
the same
time another writes, the file grows since you cannot overwrite the
previous records.
After, you execute: VACUUM ANALYZE and it will remove the old records.
Resulting, potentially in a fragmented partition!, you will have to rely
on the FS
to take care of this. A 4kb block will allow for higher resolution to
find what you need,
while 8kb can be half full many times.
Meaning, I am not sure 8kb will really help you, (aside from wasting
more space).
You will have to make more benchmarks, but also run these benchmarks
after you executed
many transactions and VACUUM s.
Good Luck.
Regards,
tzahi.
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Michael Ben-Nes
> Sent: Wednesday, September 14, 2005 10:58 AM
> To: [EMAIL PROTECTED]
> Cc: linux-il@linux.org.il
> Subject: Re: sys / db performance & block size
>
>
> After a week of testing i decided to go with JFS as the FS
> for Postgres. im not an expert benchmarker so I hope I
> initiated the right parameters
> in bonnie & pgbench.
>
> The bonnie command:
> bonnie++ -u miki -b -d /data/bonnie/ -s 6080:8k -m pr1
>
> pgbench commands:
>
> pgbench -i -s 10 test
> pgbench -c 10 -v test
> pgbench -c 10 -t 1000 -v test
>
> Any way here are the results of bonnie++ & pgbench:
>
> http://www.canaan.co.il/users/miki/stats/stats.html
>
> I couldnt create a filesystem with block size of 8k because
> my page size
> is 4k.
> Is there a way to extend the pagesize to 8k ? ( i mean
> without compiling
> the kernel ).
>
> Cheers
>
> Amos Shapira wrote:
>
> >On 9/5/05, Michael Ben-Nes <[EMAIL PROTECTED]> wrote:
> >
> >
> >>Im setting up a Postgresql sql server on IBM x345, dual
> xeon, raid1 (
> >>2 disks ), raid10 ( 4 disks ).
> >>
> >>The db data will be stored on the RAID10 and will consist
> mostly of
> >>product table of 5 mil rows and keywords table with 60 mil rows.
> >>
> >>
> >..
> >
> >
> >>I initialized the partion with reiserfs filesystem with
> block size of
> >>8192, but couldnt mount it. it kept saying:
> >>
> >>wrong fs type, bad option, bad superblock on
> /dev/VolGroup01/LV-1-0,
> >>or too many mounted file systems
> >>
> >>
> >
> >Troubleshooting your problem:
> >1. check dmesg.
> >2. Have you provided the filesystem type to mount or did you
> relay on
> >auto-detection? 3. reiserfsck?
> >
> >As for using ReiserFS for a database - I'm pretty sure that
> I read that
> >ReiserFS is considered excellent for many small files but other
> >filesystems are better with large files. You might want to
> check around
> >for reocmmandations about PostgresQL tuning (or Linux databases in
> >general). www.postgresql.org is an excellent site. Here is one page
> >there which talks about choice of filesystems:
> http://tinyurl.com/c4xes
> >and here is another one about taking advantage of multiple disk
> >spindles: http://tinyurl.com/8qjlg
> >
> >Also I think I read conflicting views about the sensibility
> of using a
> >transactional database like PostgresQL on top of a journaling
> >filesystem, I don't remember all the arguments but it might
> be that the
> >"journaling" at both levels might defeat the database's disk-access
> >atomicity.
> >
> >(And before I'll be suspected of bias - I use ReiserFS for my home
> >machine a few years now and thank god for it - it saved me a
> few times
> >when the power in my apparetment was flaky, not to mention that it
> >generally feels very fast).
> >
> >I'd be interested to know what you came up with eventually (as I
> >suspect many people on this forum).
> >
> >Cheers,
> >
> >--Amos
> >
> >===============================================================
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> >
> >
> >
>
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