* dm-crypt and huge performance penalty
@ 2010-09-20 22:37 Dmitry Nezhevenko
2010-09-22 23:52 ` Ryan Castellucci
0 siblings, 1 reply; 3+ messages in thread
From: Dmitry Nezhevenko @ 2010-09-20 22:37 UTC (permalink / raw)
To: linux-kernel
Hi,
I've just purchased three HDD drives and tried to setup mdadm RAID5 +
dm-crypt.
What I've found is that dm-crypt reduces storage I/O performance very much
while CPU is not bottleneck.
Firstly I've tried to setup raid5 and then dm-crypt on top of it. After
discovering issue I've tried just raid5 and confirmed that mdadm itself
works as expected.
And the last idea is to setup three dm-crypt partitions and then raid5 on
top of independently encrypted drives.
So here are my results:
| mdadm | mdadm+dm-crypt | 3 x dm-crypt + mdadm |
Seq. read | 168 Mb/s | 57 Mb/s | 119 Mb/s |
Seq. write | 80 Mb/s | 36 Mb/s | 64.4 Mb/s |
Also here are some results using both dd and bonnie as benchmark:
http://pastebin.com/hwwkRRTd
I'm using 3 x WD1002FAEX-00Z3A0 HDD. SATA controller is just embedded to
m/b:
00:1f.2 IDE interface: Intel Corporation 5 Series/3400 Series Chipset 4
port SATA IDE Controller (rev 06)
00:1f.5 IDE interface: Intel Corporation 5 Series/3400 Series Chipset 2
port SATA IDE Controller (rev 06)
dd tests were done using simple dd:
if=/dev/resulting-device of=/dev/zero bs=1m count=512
For Bonnie I've used 50GB reiserfs3 partition on top of resulting device.
Are these numbers expected? They looks really strange for me.
--
WBR, Dmitry
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: dm-crypt and huge performance penalty
2010-09-20 22:37 dm-crypt and huge performance penalty Dmitry Nezhevenko
@ 2010-09-22 23:52 ` Ryan Castellucci
2010-09-23 6:32 ` Dmitry Nezhevenko
0 siblings, 1 reply; 3+ messages in thread
From: Ryan Castellucci @ 2010-09-22 23:52 UTC (permalink / raw)
To: Dmitry Nezhevenko; +Cc: linux-kernel
On Mon, Sep 20, 2010 at 3:37 PM, Dmitry Nezhevenko <dion@inhex.net> wrote:
> Firstly I've tried to setup raid5 and then dm-crypt on top of it. After
> discovering issue I've tried just raid5 and confirmed that mdadm itself
> works as expected.
>
> And the last idea is to setup three dm-crypt partitions and then raid5 on
> top of independently encrypted drives.
>
> So here are my results:
>
> | mdadm | mdadm+dm-crypt | 3 x dm-crypt + mdadm |
> Seq. read | 168 Mb/s | 57 Mb/s | 119 Mb/s |
> Seq. write | 80 Mb/s | 36 Mb/s | 64.4 Mb/s |
dm-crypt will only use one core per device, so this is expected
behavior (and I believe an issue that is being worked on). From these
numbers it looks like you have a dual core or dual cpu system?
--
Ryan Castellucci http://ryanc.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: dm-crypt and huge performance penalty
2010-09-22 23:52 ` Ryan Castellucci
@ 2010-09-23 6:32 ` Dmitry Nezhevenko
0 siblings, 0 replies; 3+ messages in thread
From: Dmitry Nezhevenko @ 2010-09-23 6:32 UTC (permalink / raw)
To: Ryan Castellucci; +Cc: linux-kernel
On Wed, Sep 22, 2010 at 04:52:17PM -0700, Ryan Castellucci wrote:
> On Mon, Sep 20, 2010 at 3:37 PM, Dmitry Nezhevenko <dion@inhex.net> wrote:
> > Firstly I've tried to setup raid5 and then dm-crypt on top of it. After
> > discovering issue I've tried just raid5 and confirmed that mdadm itself
> > works as expected.
> >
> > And the last idea is to setup three dm-crypt partitions and then raid5 on
> > top of independently encrypted drives.
> >
> > So here are my results:
> >
> > | mdadm | mdadm+dm-crypt | 3 x dm-crypt + mdadm |
> > Seq. read | 168 Mb/s | 57 Mb/s | 119 Mb/s |
> > Seq. write | 80 Mb/s | 36 Mb/s | 64.4 Mb/s |
>
> dm-crypt will only use one core per device, so this is expected
> behavior (and I believe an issue that is being worked on). From these
> numbers it looks like you have a dual core or dual cpu system?
>
Hi, Yes, The machine is home NAS with inexpensive Intel Core i3 CPU that
has two real cores and HT.
--
WBR, Dmitry
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2010-09-23 6:23 UTC | newest]
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2010-09-20 22:37 dm-crypt and huge performance penalty Dmitry Nezhevenko
2010-09-22 23:52 ` Ryan Castellucci
2010-09-23 6:32 ` Dmitry Nezhevenko
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