Since you are configuring specifically for Exchange, use the "EMC CLARiiON Storage Solutions: Microsoft Exchange 2007 Best Practices Planning". This document contains the best information for that particular application. Note that this document also recommends you use RAID 1/0.

The Best Practices for Performance and Availability is a more general purpose document.

OK, The following Exchange .PDF.

But there is one question isn´t clear for me, and I would like your opnion.

But After I apply Penalty RAID 1/0 (ex 3x3). 146GB15Krpm

After Penalty each Driver ==> 120 IOPS

6 Driver ==> 720 IOPS
3 Drivers ==> First Stripe ==> 360 IOPS

In your experience, What Should I Consider to calculate IOPS?

Because I am configuring my Exchange the following Numbers of Driver versus IOPS.

Could you confirm ?

A RAID 1/0 with 146 GB 7200rpm FC drives with a 50/50 read-to-write ratio gives you 120 IOPS per drive.

How many Users do you have?

How many IOPs will they be consuming? (Are they Heavy, Medium, or Light Users?)

How big will the mailboxes be? (A 146 GB drive has 134 GB of usable capacity per drive.)

Assume 1000 Users. From Table 1. "Exchange User Profiles": 0.5 IOPS/ Heavy User, 0.3 IOPS/ Medium User, 0.2 IOPS/Light User.

RAID 1/0, 120 IOPS/Drive / 0.5 IOPS/ Heavy User = 240 Users/ Drive , 1000 Users / 240 Users/Drive ==> use 4+4 with usable capacity of 536 GB.

RAID 1/0, 120 IOPS/Drive / 0.3 IOPS/ Medium User = 400 Users/Drive, 1000 Users / 400 Users/Drive ==> use 3+3 with usable capacity of 402 GB.

RAID 1/0, 120 IOPS/Drive / 0.2 IOPS/ Light User = 600 Users/Drive, 1000 Users / 600 Users/Drive ==> use 2+2 with usable capacity of 268 GB.

OK, At the moment capacity isn´t important. I need to understand correctly to calculate.

In my case drivers 146GB 15 rpm 50/50 read/write = 180IOPS as is Table 4.

After RAID 1/0 Penalty this Drivers goes 120IOPS

In the Table 6 show in:
Users @ .5 IOPS

Applying your calculate in 4x4 ==> 180/.5 => 360 users per Driver.

So ==> 360x4 = 1440 users in RAID1/0 4x4

If I Apply the calculate from Table 6 (RAID 1/0) 4x4:

1-)120/.5 = 240
2-)240*8 = 1920 users in the RAID 1/0 4x4 to estimate .5 IOPS per users.

Question.

Is my calculate above correct?

If I want to calculate in IOPS in number of drivers.

What Should I Consider to calculate IOPS?

1-)Half (Number Total of Drivers) without RAID Penalty ? So 180IOPS
RAID 4x4 => 180x4 (First Striped) = 720IOPS

2-)Should I consider (All Drivers + RAID penalty)? So 120IOPS
RAID 4x4 ==> 120x4 (All Drivers) = 960IOPS

Did you understand me? Could you help-me?

Use Calculation #2.




180 IOPS is a value unadjusted for the read/write mix. It is the Rule-of-Thumb number used to account for many different applications IOPS requirements. When the read/write mix is unspecified, this calculation is used to approximate the RAID group's IOPS. The way the RAID group handles IOPS is approximated by only using the number of drive's in the primary stripe.



120 IOPS is the adjusted value for the read/write mix. It comes from a calculation that contains more information about how the IOPs are distributed and how the RAID-type handles IOPS. Because the calculation contains more information, it is a better approximation of performance.

I know you want 1000 IOPS. Not to confuse you, but 960 IOPS is close enough. The basic 180 IOPS per drive is a conservative number with a margin that ensures performance. If you calculate 960 IOPS, there is enough margin to easily meet a 1000 IOPS requirement.

OK Guy,,

Thank you very much