Обсуждение: What`s wrong with JFS configuration?

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What`s wrong with JFS configuration?

От
Paweł Gruszczyński
Дата:
Hello!

I have strange situation. I`m testing performance of PostgreSQL database
at  different filesystems (ext2,ex3,jfs) and I cant say that JFS is as
much faster as it is said.
My test look`s like that:

Server: 2 x Xeon 2,4GHz 2GB ram 8 x HDD SCSI configured in RAID arrays
like that:

Unit  UnitType  Status         %Cmpl  Stripe  Size(GB)  Cache  AVerify
IgnECC
------------------------------------------------------------------------------
u0    RAID-10   OK             -      64K     467.522   ON     -        -
u6    RAID-1    OK             -      -       298.09    ON     -        -

Port   Status           Unit   Size        Blocks        Serial
---------------------------------------------------------------
p0     OK               u0     233.76 GB   490234752     Y634Y1DE
p1     OK               u0     233.76 GB   490234752     Y636TR9E
p2     OK               u0     233.76 GB   490234752     Y64VZF1E
p3     OK               u0     233.76 GB   490234752     Y64G8HRE
p4     NOT-PRESENT      -      -           -             -
p5     OK               -      233.76 GB   490234752     Y63YMSNE
p6     OK               u6     298.09 GB   625142448     3QF08HFF
p7     OK               u6     298.09 GB   625142448     3QF08HHW


where u6 stores Fedora Core 6 operating system, and u0 stores 3
partitions with ext2, ext3 and jfs filesystem.
Postgresql 8.2 engine is intalled at system partition (u6 in raid) and
run with data directory at diffrent FS partition for particular test.
To test I use pgBench with default database schema, run for 25, 50, 75
users at one time. Every test I run 5 time to take average.
Unfortunetly my result shows that ext is fastest, ext3 and jfs are very
simillar. I can understand that ext2 without jurnaling is faster than
ext3, it is said that jfs is 40 - 60% faster. I cant see the difference.
Part of My results: (transaction type | scaling factor | num of clients
| tpl | num on transactions | tps including connection time | tps
excliding connection time)

EXT2:

TPC-B (sort of),50,75,13,975|975,338.286682,358.855582
TPC-B (sort of),50,75,133,9975|9975,126.777438,127.023687
TPC-B (sort of),50,75,1333,99975|99975,125.612325,125.636193

EXT3:

TPC-B (sort of),50,75,13,975|975,226.139237,244.619009
TPC-B (sort of),50,75,133,9975|9975,88.678922,88.935371
TPC-B (sort of),50,75,1333,99975|99975,79.126892,79.147423

JFS:

TPC-B (sort of),50,75,13,975|975,235.626369,255.863271
TPC-B (sort of),50,75,133,9975|9975,88.408323,88.664584
TPC-B (sort of),50,75,1333,99975|99975,81.003394,81.024297


Can anyone tell me what`s wrong with my test? Or maybe it is normal?

Pawel Gruszczynski

Re: What`s wrong with JFS configuration?

От
Heikki Linnakangas
Дата:
Paweł Gruszczyński wrote:
> To test I use pgBench with default database schema, run for 25, 50, 75
> users at one time. Every test I run 5 time to take average.
> Unfortunetly my result shows that ext is fastest, ext3 and jfs are very
> simillar. I can understand that ext2 without jurnaling is faster than
> ext3, it is said that jfs is 40 - 60% faster. I cant see the difference.
> Part of My results: (transaction type | scaling factor | num of clients
> | tpl | num on transactions | tps including connection time | tps
> excliding connection time)
>
> EXT2:
>
> TPC-B (sort of),50,75,13,975|975,338.286682,358.855582
> ...
>
> Can anyone tell me what`s wrong with my test? Or maybe it is normal?

With a scaling factor of 50, your database size is ~ 1 GB, which fits
comfortably in your RAM. You're not exercising your drives or filesystem
much. Assuming you haven't disabled fsync, the performance of that test
is bound by the speed your drives can flush WAL commit records to disk.

I wouldn't expect the filesystem to make a big difference anyway, but
you'll see..

--
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

Re: What`s wrong with JFS configuration?

От
Dave Cramer
Дата:
On 25-Apr-07, at 4:54 AM, Heikki Linnakangas wrote:

> Paweł Gruszczyński wrote:
>> To test I use pgBench with default database schema, run for 25,
>> 50, 75 users at one time. Every test I run 5 time to take average.
>> Unfortunetly my result shows that ext is fastest, ext3 and jfs are
>> very simillar. I can understand that ext2 without jurnaling is
>> faster than ext3, it is said that jfs is 40 - 60% faster. I cant
>> see the difference. Part of My results: (transaction type |
>> scaling factor | num of clients | tpl | num on transactions | tps
>> including connection time | tps excliding connection time)
>> EXT2:
>> TPC-B (sort of),50,75,13,975|975,338.286682,358.855582
>> ...
>> Can anyone tell me what`s wrong with my test? Or maybe it is normal?
>
> With a scaling factor of 50, your database size is ~ 1 GB, which
> fits comfortably in your RAM. You're not exercising your drives or
> filesystem much. Assuming you haven't disabled fsync, the
> performance of that test is bound by the speed your drives can
> flush WAL commit records to disk.
>
> I wouldn't expect the filesystem to make a big difference anyway,
> but you'll see..

If you really believe that jfs is 40 -60% faster ( which I highly
doubt ) you should see this by simply reading/writing a very large
file (2x your memory size) with dd .

Just curious but what data do you have that suggests this 40-60%
number ?

Dave
>
> --
>   Heikki Linnakangas
>   EnterpriseDB   http://www.enterprisedb.com
>
> ---------------------------(end of
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>
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Re: What`s wrong with JFS configuration?

От
Paweł Gruszczyński
Дата:
Alexander Staubo napisał(a):
> On 4/25/07, Paweł Gruszczyński <> wrote:
>> I have strange situation. I`m testing performance of PostgreSQL database
>> at  different filesystems (ext2,ex3,jfs) and I cant say that JFS is as
>> much faster as it is said.
>
> I don't know about 40-60% faster, but JFS is known to be a fast, good
> file system -- faster than other file systems for some things, slower
> for others. It's particularly known for putting a somewhat lower load
> on the CPU than most other journaling file systems.
>
> Alexander.
>
I was just reading some informations on the web (for example:
http://www.nabble.com/a-comparison-of-ext3,-jfs,-and-xfs-on-hardware-raid-t144738.html).

My test should tell mi if it`s true, but now I see that rather everyhing
is ok with my test method and the gain of using JFS is not so high.

Pawel

Re: What`s wrong with JFS configuration?

От
Chris Browne
Дата:
 (Paweł Gruszczyński) writes:
> To test I use pgBench with default database schema, run for 25, 50, 75
> users at one time. Every test I run 5 time to take average.
> Unfortunetly my result shows that ext is fastest, ext3 and jfs are
> very simillar. I can understand that ext2 without jurnaling is faster
> than ext3, it is said that jfs is 40 - 60% faster. I cant see the
> difference. Part of My results: (transaction type | scaling factor |
> num of clients | tpl | num on transactions | tps including connection
> time | tps excliding connection time)
>
> EXT2:
>
> TPC-B (sort of),50,75,13,975|975,338.286682,358.855582
> TPC-B (sort of),50,75,133,9975|9975,126.777438,127.023687
> TPC-B (sort of),50,75,1333,99975|99975,125.612325,125.636193
>
> EXT3:
>
> TPC-B (sort of),50,75,13,975|975,226.139237,244.619009
> TPC-B (sort of),50,75,133,9975|9975,88.678922,88.935371
> TPC-B (sort of),50,75,1333,99975|99975,79.126892,79.147423
>
> JFS:
>
> TPC-B (sort of),50,75,13,975|975,235.626369,255.863271
> TPC-B (sort of),50,75,133,9975|9975,88.408323,88.664584
> TPC-B (sort of),50,75,1333,99975|99975,81.003394,81.024297
>
>
> Can anyone tell me what`s wrong with my test? Or maybe it is normal?

For one thing, this test is *probably* staying mostly in memory.  That
will be skewing results away from measuring anything about the
filesystem.

When I did some testing of comparative Linux filesystem performance,
back in 2003, I found that JFS was maybe 20% percent faster on a
"write-only" workload than XFS, which was a few percent faster than
ext3.  The differences weren't terribly large.

If you're seeing such huge differences with pgbench (which includes
read load, which should be virtually unaffected by one's choice of
filesystem), then I can only conclude that something about your
testing methodology is magnifying the differences.
--
let name="cbbrowne" and tld="cbbrowne.com" in String.concat "@" [name;tld];;
http://cbbrowne.com/info/oses.html
"On the Internet, no one knows you're using Windows NT"
-- Ramiro Estrugo, 

Re: What`s wrong with JFS configuration?

От
Greg Smith
Дата:
On Wed, 25 Apr 2007, Pawe�~B Gruszczy�~Dski wrote:

> I was just reading some informations on the web (for example:
> http://www.nabble.com/a-comparison-of-ext3,-jfs,-and-xfs-on-hardware-raid-t144738.html).

You were doing your tests with a database scale of 50.  As Heikki already
pointed out, that's pretty small (around 800MB) and you're mostly
stressing parts of the system that may not change much based on filesystem
choice.  This is even more true when some of your tests are only using a
small amount of transactions in a short period of time, which means just
about everything could still be sitting in memory at the end of the test
with the database disks barely used.

In the example you reference above, a scaling factor of 1000 was used.
This makes for a fairly large database of about 16GB.  When running in
that configuration, as stated he's mostly testing seek performance--you
can't hold any significant portion of 16GB in memory, so you're always
moving around the disks to find the data needed.  It's a completely
different type of test than what you did.

If you want to try and replicate the filesystem differences shown on that
page, start with the bonnie++ tests and see if you get similar results
there.  It's hard to predict whether you'll see the same differences given
how different your RAID setup is from Jeff Baker's tests.

It's not a quick trip from there to check if an improvement there holds up
in database use that's like a real-world load.  In addition to addressing
the scaling factor issue, you'll need to so some basic PostgreSQL
parameter tuning from the defaults, think about the impact of checkpoints
on your test, and worry about whether your WAL I/O is being done
efficiently before you get to the point where the database I/O is being
measured usefully at all via pgbench.

--
* Greg Smith  http://www.gregsmith.com Baltimore, MD

Re: What`s wrong with JFS configuration?

От
Jim Nasby
Дата:
On Apr 25, 2007, at 8:51 AM, Paweł Gruszczyński wrote:
> where u6 stores Fedora Core 6 operating system, and u0 stores 3
> partitions with ext2, ext3 and jfs filesystem.

Keep in mind that drives have a faster data transfer rate at the
outer-edge than they do at the inner edge, so if you've got all 3
filesystems sitting on that array at the same time it's not a fair
test. I heard numbers on the impact of this a *long* time ago and I
think it was in the 10% range, but I could be remembering wrong.

You'll need to drop each filesystem and create the next one to get a
fair comparison.
--
Jim Nasby                                            
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)



Re: What`s wrong with JFS configuration?

От
"Luke Lonergan"
Дата:

The outer track / inner track performance ratio is more like 40 percent.  Recent example is 78MB/s outer and 44MB/s inner for the new Seagate 750MB drive (see http://www.storagereview.com for benchmark results)

- Luke

Msg is shrt cuz m on ma treo

 -----Original Message-----
From:   Jim Nasby [mailto:]
Sent:   Thursday, April 26, 2007 03:53 AM Eastern Standard Time
To:     Pawel Gruszczynski
Cc:    
Subject:        Re: [PERFORM] What`s wrong with JFS configuration?

On Apr 25, 2007, at 8:51 AM, Pawel Gruszczynski wrote:
> where u6 stores Fedora Core 6 operating system, and u0 stores 3 
> partitions with ext2, ext3 and jfs filesystem.

Keep in mind that drives have a faster data transfer rate at the 
outer-edge than they do at the inner edge, so if you've got all 3 
filesystems sitting on that array at the same time it's not a fair 
test. I heard numbers on the impact of this a *long* time ago and I 
think it was in the 10% range, but I could be remembering wrong.

You'll need to drop each filesystem and create the next one to get a 
fair comparison.
--
Jim Nasby                                           
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)



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Re: What`s wrong with JFS configuration?

От
Cosimo Streppone
Дата:
Jim Nasby wrote:

> On Apr 25, 2007, at 8:51 AM, Paweł Gruszczyński wrote:
>> where u6 stores Fedora Core 6 operating system, and u0 stores 3
>> partitions with ext2, ext3 and jfs filesystem.
>
> Keep in mind that drives have a faster data transfer rate at the
> outer-edge than they do at the inner edge [...]

I've been wondering from time to time if partitions position
can be a (probably modest, of course) performance gain factor.

If I create a partition at the beginning or end of the disk,
is this going to have a determined platter physical position?

I remember having heard that every manufacturer has its own
allocation logic.

Has anyone got some information, just for curiosity?

--
Cosimo


Re: What`s wrong with JFS configuration?

От
Jim Nasby
Дата:
Adding -performance back in so others can learn.

On Apr 26, 2007, at 9:40 AM, Paweł Gruszczyński wrote:

> Jim Nasby napisał(a):
>> On Apr 25, 2007, at 8:51 AM, Paweł Gruszczyński wrote:
>>> where u6 stores Fedora Core 6 operating system, and u0 stores 3
>>> partitions with ext2, ext3 and jfs filesystem.
>>
>> Keep in mind that drives have a faster data transfer rate at the
>> outer-edge than they do at the inner edge, so if you've got all 3
>> filesystems sitting on that array at the same time it's not a fair
>> test. I heard numbers on the impact of this a *long* time ago and
>> I think it was in the 10% range, but I could be remembering wrong.
>>
>> You'll need to drop each filesystem and create the next one go get
>> a fair comparison.
>
> I thought about it by my situation is not so clear, becouse my hard
> drive for postgresql data is rather "logical" becouse of RAID array
> i mode 1+0. My RAID Array is divided like this:
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sda1               1      159850   163686384   83  Linux
> /dev/sda2          159851      319431   163410944   83  Linux
> /dev/sda3          319432      478742   163134464   83  Linux
>
> and partitions are:
>
> /dev/sda1     ext2   161117780   5781744 147151720   4% /fs/ext2
> /dev/sda2     ext3   160846452   2147848 150528060   2% /fs/ext3
> /dev/sda3      jfs   163096512   3913252 159183260   3% /fs/jfs
>
> so if RAID 1+0 do not change enything, JFS file system is at third
> partition wich is at the end of hard drive.

Yes, which means that JFS is going to be at a disadvantage to ext3,
which will be at a disadvantage to ext2. You should really re-perform
the tests with each filesystem in the same location.

> What about HDD with two magnetic disk`s? Then the speed depending
> of partition phisical location is more difficult to calculate ;)
> Propably first is slow, secund is fast in firs halt and slow in
> secund halt, third is the fastes one. In both cases my JFS partitin
> should be ath the end on magnetic disk. Am I wrong?

I'm not a HDD expert, but as far as I know the number of platters
doesn't change anything. When you have multiple platters, the drive
essentially splits bytes across all the platters; it doesn't start
writing one platter, then switch to another platter.
--
Jim Nasby                                            
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)