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Here is one way to look at it..
Good Article!


This shows the fundamental problem with raid 10. Everything acts as one volume. All the IO is shared between all the drives of the redundant mirror. Thus giving you one big expensive and slow volume. This is because every read / write has to happen to every signal drive in the storage array.

you take the same 20 drives split it to 10 raid1 volumes and you now have 10 independent IO unites.

I had this argument with my own boss happy He wanted me to make our new 6tb SATA storage array one large raid 5 volume. The array consists of 12 SATA drvies and we use it for spooling backup jobs before going to tape and for temporary retention.

The issues is that sata drives don't have very good IO to start with and i have determined that i can only have 4 readers / writers set per array. So by breaking up the same array to thee arrays i can backup 12 servers / desktops at a time. At the expense of loosing 1 tb of space (each drive is 500 megs). Not to mention the fact that having 12 drives in a raid 5 probably gives you a failure rate greater than that of a signal drive!
Posted by: mightofnight@...   Posted on: 05/04/07 You are currently: a Guest | Members login | Terms of Use
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Here is one way to look at it..  mightofnight@... | 05/04/07
Yup, hard to go against "conventional wisdom"  georgeou | 05/04/07
RAID 10  geblack | 05/07/07
Soo....  nucrash | 05/04/07
Of course, that's what page 1 says  georgeou | 05/04/07
Toy benchmarks...  Mad Dan | 05/04/07
That's what they all say  georgeou | 05/04/07
CPU performance due to parity calculations with HW RAID?  ye | 05/04/07
Onboard Raid lacks an XO co-processor....  JoeMama_z | 05/04/07
Then why is it considered HW RAID if the RAID...  ye | 05/04/07
depends who is describing it....  JoeMama_z | 05/04/07
This is driver-level RAID  georgeou | 05/04/07
It's technically not HW RAID  georgeou | 05/04/07
Then it's not the XOR that's driving the CPU to 35% but...  ye | 05/04/07
RAID5 high-throughput write is the hardest on the CPU  georgeou | 05/04/07
That's because of the many I/O transactions required...  ye | 05/05/07
Sorry, software RAID and no-TOE is used in Enterprise solutions  georgeou | 05/04/07
I was mainly pointing to your choice of desktop board...  JoeMama_z | 05/04/07
Again,there NO difference  georgeou | 05/04/07
HW raid and parity calculations.  geoffr@... | 05/04/07
That's no longer true  georgeou | 05/04/07
Why didn't you try  JoeMama_z | 05/04/07
RAID10 is RAID1+0  georgeou | 05/04/07
Any news on those Linux drivers?  odubtaig | 05/04/07
There are ICH7R drivers but not sure about ICH8R for Linux  georgeou | 05/04/07
Think I've got it this time happy  odubtaig | 05/06/07
Testing is completely invalid  cornpie | 05/04/07
You drank the "enterprise" kool-aid  georgeou | 05/04/07
Testing still invalid  cornpie | 05/04/07
Yeah, and what is a "real" array?  georgeou | 05/04/07
First sign of a "real" RAID server is  Sxooter_z | 05/08/07
"Real" RAID  AgentDuke | 05/09/07
I've tests plenty of "real" servers  georgeou | 05/09/07
What work?  gordon@... | 05/07/07
Do you always ignore multimedia?  CobraA1 | 05/04/07
FYI, look at page 1  georgeou | 05/04/07
Pretty small side note  CobraA1 | 05/04/07
I think offloaders are dying  georgeou | 05/04/07
Many servers...  Justin James | 05/04/07
I think SuperMicro uses Marvell software RAID  georgeou | 05/04/07
Oops, confused data allocation randomisation with 'striping'  odubtaig | 05/04/07
Clicked the wrong reply button too *thwonk* NT  odubtaig | 05/04/07
It's completely different  georgeou | 05/04/07
Fixed post here  georgeou | 05/04/07
Message has been deleted.  nomorems | 05/04/07
You keep this offensive spam up and we'll have to ban you  georgeou | 05/04/07
I'd like this moron banned  Xwindowsjunkie | 05/05/07
He's getting real close if he keeps spamming the same message  georgeou | 05/05/07
HOW'S THIS FOR REAL-WORLD IT  solar_satellite | 05/05/07
Pardon? We don't require you install anything.  georgeou | 05/05/07
And this has what to do with the RAID article?  DrMicro | 05/06/07
Good Story George  Xwindowsjunkie | 05/05/07
Thanks, even high-performance RAID controllers are slow on RAID5  georgeou | 05/05/07
I'll be changing my RAID  DrMicro | 05/06/07
ICH7R is almost as good as ICH8R  georgeou | 05/06/07
ICH7R is almost as good as ICH8R  supremelaw | 05/06/07
Raid 5 capacity upgrade ?  shakewell | 05/06/07
You can, but only up to 4 drives.  georgeou | 05/06/07
Why the numbers could be suspect.  civikminded | 05/06/07
That wasn't the reason for that Fortune 100  georgeou | 05/06/07
Terminology  civikminded | 05/06/07
Outstanding IOs never hit that high  georgeou | 05/06/07
Where x86 cannot replace hardware offload  Liam Newcombe | 05/07/07
Wake up folks - SSD is here  Gene(ius):) | 05/07/07
Cost prohibitive  geblack | 05/07/07
Not so.  gordon@... | 05/07/07
SSDs have merit, but they have issues like number of rewrites  georgeou | 05/07/07
row-level striping  geblack | 05/07/07
It's also known as Horizontal Data Partitioning  odubtaig | 05/07/07
Data Partitioning  geblack | 05/07/07
Sql 2000  geblack | 05/07/07
Yes, 2 years ago, it was SQL2K  georgeou | 05/07/07
Files/filegroups  geblack | 05/07/07
No no, that's not it  georgeou | 05/07/07
Not files/filegroups  geblack | 05/07/07
There are no commands, it's built in to the management UI.  georgeou | 05/07/07
According to George  geblack | 05/08/07
Lose the 3D graphs  ejb78923 | 05/07/07
Why?  georgeou | 05/07/07
Server RAID  billyato@... | 05/07/07
Write intensive  geblack | 05/07/07
Depends on writebackcaching or writethroughcaching  georgeou | 05/07/07
Finishing post here  georgeou | 05/07/07
SAS RAID5 performance  billyato@... | 05/07/07
There's throughput, and then there's I/O performance  georgeou | 05/07/07
SAS RAID 5 is different  billyato@... | 05/07/07
No no no, you totally missed it  georgeou | 05/07/07
Nice one, George!  yanipen@... | 05/07/07
Thanks, it will be posted on TR as a downloadable PDF  georgeou | 05/07/07
Different Controllers have Different Strengths  Sxooter_z | 05/08/07
Thank you  geblack | 05/08/07
Again, these tests show IOMeter results  georgeou | 05/09/07
A Few Fundamental Things  DoubleJava | 05/09/07
Nonsense, I'd just use even more RAID1 pairs  georgeou | 05/09/07
logs  rdupuy11 | 04/23/09
Parallel to your MS-SQL story  Sxooter_z | 05/09/07
That's called short stroking  georgeou | 05/09/07
But that's not what happened  Sxooter_z | 06/07/07
"Real" RAID  AgentDuke | 05/09/07
File system alignment  dj_meier | 05/09/07
IO was much smaller than stripe size  georgeou | 05/09/07
Alignment  dj_meier | 05/10/07
My own test results  dj_meier | 05/09/07
29% better on random read IO is not "slightly better"  georgeou | 05/09/07
Correcting myself  georgeou | 05/10/07
I agree with the 29% number  dj_meier | 05/10/07
Apples to apples?  pwinn | 06/08/07
Soft partitions slow you down even more  georgeou | 06/15/07
If I read this right  kmatzen@... | 05/09/07
Almost  georgeou | 05/09/07
Not enough spindles  Dave P. | 05/12/07
Why?  dj_meier | 05/16/07
Good question, but I have to be honest, I can't explain  georgeou | 05/28/07
Any headway...  MrE. | 05/29/07
You merely assign multiple physical volumes to a database  georgeou | 06/15/07
How about a straight answer...  dfgjohnson | 07/08/07
What about using LVM across mult Raid1's  srj@... | 06/21/07
Storage multi-threading...  evodico | 07/05/07
article application to desktop set-up and pair raid1 set-up  p_byford@... | 02/04/08
RE: Comprehensive RAID performance report  nat@... | 02/20/08
Seamless data table distribution???  chamblee | 06/05/08
RE: Comprehensive RAID performance report  dontek | 10/23/08
Nevermind, I answered this for myself 5 minutes after posting...  dontek | 10/23/08
Another Question on Splitting Databases  dontek | 10/23/08
A small insight (I hope)  klauss4 | 02/27/09
Excellent still in 2009!!!  lionel2 | 03/20/09
Oracle comment is wrong  rdupuy11 | 04/23/09
p.s.  rdupuy11 | 04/23/09

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