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Re: Recommended/Not Recommended Hosts?

From: Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>
To: Jason DiCioccio <jd(at)ods(dot)org>
Cc: Sailesh Krishnamurthy <sailesh(at)gmail(dot)com>, Josh Livni <josh(at)umbrellaconsulting(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, SF Postgres <sfpug(at)postgresql(dot)org>
Subject: Re: Recommended/Not Recommended Hosts?
Date: 2009-12-12 01:14:06
Message-ID: 4B22EE5E.2010405@cheapcomplexdevices.com (view raw or flat)
Thread:
Lists: sfpug
Jason DiCioccio wrote:
> On Fri, Dec 11, 2009 at 15:48, Sailesh Krishnamurthy <sailesh(at)gmail(dot)com> wrote:
>> Has anyone used EBS on EC2 ?
>> I/O is supposed to be much better on it
> 
> My testing has shown it to still be pretty awful.  Although Amazon
> does suggest doing software RAID on multiple EBS volumes.  I haven't
> tried that yet.

The one thing I love about EC2 is that it's incredibly easy and
cheap to test such things.   I just tried it for the cost of about $0.20.

 (the script I used, and output from bonnie++ below)

Seek performance on the non-EBS default drive is poor -- but if I'm
reading the bonnie++ output right, the EBS volume otherwise wasn't
really faster - and perhaps even slower than the default drive for block
reads and writes.   Also if I read the bonnie++ output right, strangely,
block reads seem much slower with a 7-EBS-volume RAID array than with a
single EBS block.  RAID helped the writes significantly, though.

Does that make sense?   Can anyone help me interpret that output?

All this was on a small instance (which end up with low I/O and CPU priority),
so I guess it's quite possible this test was dominated with people running more
expensive instances stealing the CPU and I/O resources.




Here's the script I just used after attaching 7 EBS volumes to one of my
instances:
================================================================================
sudo mdadm --create /dev/md0 --level=0 --raid-devices=7 /dev/sdb1  /dev/sdb2  /dev/sdb3  /dev/sdb4  /dev/sdb5  /dev/sdb6  /dev/sdb7
sudo mkfs.ext3 /dev/md0
sudo mkdir /mnt/md0
sudo tune2fs -o journal_data_writeback /dev/md0
sudo mount /dev/md0 /mnt/md0
sudo chmod a+w /mnt/md0
cd /mnt/md0
bonnie++ -d /mnt/md0
================================================================================

And here's the output:

================================================================================
= 1 local disk on EC2 small instance
===============================================================================
Version 1.03c       ------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
ars.forensicl 3408M 21139  35 65132  11 31224   2 24915  19 70138   1 189.1   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
ars.forensiclogic.com,3408M,21139,35,65132,11,31224,2,24915,19,70138,1,189.1,0,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++

================================================================================
= 1 EBS disk on EC2 small instance
===============================================================================

Version 1.03c       ------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
ars.forensicl 3408M 22239  34 40111   5 17178   0 23539  17 51379   0 570.1   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
ars.forensiclogic.com,3408M,22239,34,40111,5,17178,0,23539,17,51379,0,570.1,0,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++

================================================================================
= RAID0 of 7 EBS disks on EC2 small instance
===============================================================================

Version 1.03c       ------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
ars.forensicl 3408M 20884  34 115135  24 17586   1 15472  20 23198   0  5659   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 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
ars.forensiclogic.com,3408M,20884,34,115135,24,17586,1,15472,20,23198,0,5659.1,1,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++



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