2001-04-13 11:40:51

by Andreas Peter

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Subject: SW-RAID0 Performance problems

Hi,
I've successfully set up SW-RAID0 with Kernel 2.4.3 and Raidtools 0.9.
I did this to increase the performance of my HD, but nothig happens.
The hdparm results:
hdparm -t /dev/md0 : 20.25 MB/sec
hdparm -t /dev/hda : 20.51 MB/sec
hdaprm -t /dev/hdc : 20.71 MB/sec

I thougt the performnace of RAID0 should near 40MB/sec.
I played with different chunk-sizes, but the result was everytime the same.
The drives are both Maxtor DiamondMax VL40, 30GB, DMA on.
No other drive is attached on the bus.

Here are also some bonnie++ results:


-- RAID-0 --
-- chunk-size=16 --

Version 1.01 ------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
debian 1G 7416 99 14277 20 7498 10 6942 90 27007 20 113.0 1
------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 267 99 +++++ +++ 10968 100 269 99 +++++ +++ 1388 99

-- chunk-size=32 --

Version 1.01 ------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
debian 1G 7396 99 14075 20 7469 10 6945 90 26960 20 133.7 1
------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 265 100 +++++ +++ 10695 99 267 99 +++++ +++ 1447 100

-- Single HD /dev/hdc1 --

Version 1.01 ------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
debian 1G 7173 96 11055 13 5038 6 5999 78 29146 21 90.7 1
------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 272 100 +++++ +++ 10482 99 274 99 +++++ +++ 1437 100

Are there known performanace problems with 2.4.3, or is it necessary to
apply patches to the kernel?
Or did I something wrong??
Thank you for every hint!

Andreas
--
Andreas Peter *** [email protected]


2001-04-13 15:30:31

by Andreas Peter

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Subject: Re: SW-RAID0 Performance problems

Mark Hahn schrieb:
> > hdparm -t /dev/md0 : 20.25 MB/sec
> > hdparm -t /dev/hda : 20.51 MB/sec
> > hdaprm -t /dev/hdc : 20.71 MB/sec
>
> md0 is composed of partitions located where on hda and hdc?
> also, what's your CPU?

This is my raidtab file:

raiddev /dev/md0

raid-level 0 # it's not obvious but this *must* be
# right after raiddev

persistent-superblock 1 # set this to 1 if you want autostart,
# BUT SETTING TO 1 WILL DESTROY PREVIOUS
# CONTENTS if this is a RAID0 array created
# by older raidtools (0.40-0.51) or mdtools!

chunk-size 32

nr-raid-disks 2
nr-spare-disks 0

device /dev/hda3
raid-disk 0

device /dev/hdc3
raid-disk 1

The partition table:

Disk /dev/hda: 16 heads, 63 sectors, 59556 cylinders
Units = cylinders of 1008 * 512 bytes

Device Boot Start End Blocks Id System
/dev/hda1 * 1 21 10552+ 83 Linux
/dev/hda2 22 542 262584 82 Linux swap
/dev/hda3 543 59556 29743056 fd Linux raid autodetect

My board is a Gigabyte 6BXDS BX-Chipset 2 Celerons@533 MHz

Andreas
--
Andreas Peter *** [email protected]

2001-04-13 16:02:17

by Jakob Oestergaard

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Subject: Re: SW-RAID0 Performance problems

On Fri, Apr 13, 2001 at 01:47:30PM +0200, Andreas Peter wrote:
> Hi,
> I've successfully set up SW-RAID0 with Kernel 2.4.3 and Raidtools 0.9.
> I did this to increase the performance of my HD, but nothig happens.
> The hdparm results:
> hdparm -t /dev/md0 : 20.25 MB/sec
> hdparm -t /dev/hda : 20.51 MB/sec
> hdaprm -t /dev/hdc : 20.71 MB/sec
>
> I thougt the performnace of RAID0 should near 40MB/sec.
> I played with different chunk-sizes, but the result was everytime the same.
> The drives are both Maxtor DiamondMax VL40, 30GB, DMA on.
> No other drive is attached on the bus.
>
> Here are also some bonnie++ results:
...

I can't say much about this... It looks like your setup is perfectly allright,
and the performance *should* go up. Instead it looks like you get a small
performance drop from using the RAID. Most odd.

Do you have more controllers in the machine ? If so could you try to move eg.
hdc to the second controller ? The only thing I can imagine being the cause of
the poor performance is, if your controller somehow doesn't handle both
channels very well simultaneously. It's far fetched, but it's the only
suggestion I can think of.

Maybe Andre has comments ?

I usually get a good speedup from using RAID-0 on 2.4.3 with IDE. Both with
two disks and with six. This is with Intel PIIX4 and Promise 20262
controllers.

--
................................................................
: [email protected] : And I see the elder races, :
:.........................: putrid forms of man :
: Jakob ?stergaard : See him rise and claim the earth, :
: OZ9ABN : his downfall is at hand. :
:.........................:............{Konkhra}...............:

2001-04-13 16:08:18

by David Rees

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Subject: Re: SW-RAID0 Performance problems

On Fri, Apr 13, 2001 at 05:36:55PM +0200, Andreas Peter wrote:
> Mark Hahn schrieb:
> > > hdparm -t /dev/md0 : 20.25 MB/sec
> > > hdparm -t /dev/hda : 20.51 MB/sec
> > > hdaprm -t /dev/hdc : 20.71 MB/sec
> >
> > md0 is composed of partitions located where on hda and hdc?
> > also, what's your CPU?
>
> This is my raidtab file:

<snip>

Cconfig and setup looks OK.

What happens if your run hdparm -t /dev/hda and /dev/hdc at the same time?

-Dave

2001-04-13 16:22:00

by Andreas Peter

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Subject: Re: SW-RAID0 Performance problems

Am Freitag, 13. April 2001 18:01 schrieb Jakob ?stergaard:

> I can't say much about this... It looks like your setup is perfectly
> allright, and the performance *should* go up. Instead it looks like you
> get a small performance drop from using the RAID. Most odd.
>
> Do you have more controllers in the machine ? If so could you try to move
> eg. hdc to the second controller ? The only thing I can imagine being the
> cause of the poor performance is, if your controller somehow doesn't handle
> both channels very well simultaneously. It's far fetched, but it's the
> only suggestion I can think of.

The Board ist a Gigabyte 6BXDS (BX-Chipset) and 2 Celeron 533
I think the hardware is ok.

> I usually get a good speedup from using RAID-0 on 2.4.3 with IDE. Both
> with two disks and with six. This is with Intel PIIX4 and Promise 20262
> controllers.

Andreas
--
Andreas Peter *** [email protected]

2001-04-13 16:21:30

by Andreas Peter

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Subject: Re: SW-RAID0 Performance problems

Am Freitag, 13. April 2001 18:07 schrieb David Rees:

> Cconfig and setup looks OK.
>
> What happens if your run hdparm -t /dev/hda and /dev/hdc at the same time?

Good idea!
The performance is only ~11MB/sec per disk
There is a bottleneck somewhere...

Andreas
--
Andreas Peter *** [email protected]

2001-04-13 18:12:16

by Tim Moore

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Subject: Re: SW-RAID0 Performance problems

David Rees wrote:
> What happens if your run hdparm -t /dev/hda and /dev/hdc at the same time?

Try 'hdparm -tT' with simultaneous /dev/hda3 and /dev/hdc3. This gives you
a baseline on the actual partitions involved.

rgds,
tim.
--

2001-04-14 07:05:12

by David Rees

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Subject: Re: SW-RAID0 Performance problems

On Fri, Apr 13, 2001 at 06:28:20PM +0200, Andreas Peter wrote:
> Am Freitag, 13. April 2001 18:07 schrieb David Rees:
>
> > Cconfig and setup looks OK.
> >
> > What happens if your run hdparm -t /dev/hda and /dev/hdc at the same time?
>
> Good idea!
> The performance is only ~11MB/sec per disk
> There is a bottleneck somewhere...

OK, so it's not the RAID setup. There's two things that can cause this.
One is that DMA is turned off (what does hdparm /dev/hda and hdparm
/dev/hdc show?), the second was that the drives are on the same channel
(which obviously isn't the case here). Can you verify that the drives are
in DMA mode?

-Dave

2001-04-14 09:31:17

by Andreas Peter

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Subject: Re: SW-RAID0 Performance problems

Am Samstag, 14. April 2001 09:04 schrieb David Rees:

> OK, so it's not the RAID setup. There's two things that can cause this.
> One is that DMA is turned off (what does hdparm /dev/hda and hdparm
> /dev/hdc show?), the second was that the drives are on the same channel
> (which obviously isn't the case here). Can you verify that the drives are
> in DMA mode?

hdparm /dev/hda

/dev/hda:
multcount = 16 (on)
I/O support = 0 (default 16-bit)
unmaskirq = 0 (off)
using_dma = 1 (on)
keepsettings = 0 (off)
nowerr = 0 (off)
readonly = 0 (off)
readahead = 8 (on)
geometry = 59556/16/63, sectors = 60032448, start = 0

the same on /dev/hdc

I played with different hdparm-settings, but it's not possible to speed up
the HDs

Andreas
--
Andreas Peter *** [email protected]

2001-04-14 10:38:16

by Andreas Peter

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Subject: Re: SW-RAID0 Performance problems

Am Freitag, 13. April 2001 20:11 schrieb Tim Moore:

> Try 'hdparm -tT' with simultaneous /dev/hda3 and /dev/hdc3. This gives
> you a baseline on the actual partitions involved.

hdparm -tT simultanous on /dev/hda3 and /dev/hdc3:

/dev/hda3:
Timing buffer-cache reads: 128 MB in 2.29 seconds = 55.90 MB/sec
Timing buffered disk reads: 64 MB in 4.67 seconds = 13.70 MB/sec

/dev/hdc3:
Timing buffer-cache reads: 128 MB in 2.28 seconds = 56.14 MB/sec
Timing buffered disk reads: 64 MB in 4.61 seconds = 13.88 MB/sec

Now on single HD - /dev/hda3 :

/dev/hda3:
Timing buffer-cache reads: 128 MB in 1.30 seconds = 98.46 MB/sec
Timing buffered disk reads: 64 MB in 2.26 seconds = 28.32 MB/sec

It looks like reading on /dev/hda3 locks /dev/hdc3 ...
Is it necessary to apply the ide-patches to the kernel ?

Andreas
--
Andreas Peter *** [email protected]

2001-04-14 12:29:12

by Kurt Roeckx

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Subject: Re: SW-RAID0 Performance problems

On Sat, Apr 14, 2001 at 11:38:06AM +0200, Andreas Peter wrote:
> Am Samstag, 14. April 2001 09:04 schrieb David Rees:
>
> > OK, so it's not the RAID setup. There's two things that can cause this.
> > One is that DMA is turned off (what does hdparm /dev/hda and hdparm
> > /dev/hdc show?), the second was that the drives are on the same channel
> > (which obviously isn't the case here). Can you verify that the drives are
> > in DMA mode?
>
> hdparm /dev/hda
>
> /dev/hda:
> multcount = 16 (on)
> I/O support = 0 (default 16-bit)
> unmaskirq = 0 (off)
> using_dma = 1 (on)

Does turning unmaskirq on help?


Kurt

2001-04-14 13:02:51

by Andreas Peter

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Subject: Re: SW-RAID0 Performance problems

Am Samstag, 14. April 2001 14:28 schrieb Kurt Roeckx:
> Does turning unmaskirq on help?

Already tried this, but it doesn't help
The actual settings (same on /dev/hdc):

bash-2.04# hdparm /dev/hda

/dev/hda:
multcount = 16 (on)
I/O support = 1 (32-bit)
unmaskirq = 1 (on)
using_dma = 1 (on)
keepsettings = 0 (off)
nowerr = 0 (off)
readonly = 0 (off)
readahead = 8 (on)
geometry = 59556/16/63, sectors = 60032448, start = 0

bash-2.04# hdparm -tT /dev/md0

/dev/md0:
Timing buffer-cache reads: 128 MB in 1.30 seconds = 98.46 MB/sec
Timing buffered disk reads: 64 MB in 3.14 seconds = 20.38 MB/sec

bash-2.04# hdparm -tT /dev/hda3

/dev/hda3:
Timing buffer-cache reads: 128 MB in 1.31 seconds = 97.71 MB/sec
Timing buffered disk reads: 64 MB in 2.26 seconds = 28.32 MB/sec

Andreas
--
Andreas Peter *** [email protected]