This document discusses using BVQ software to analyze disk performance metrics in order to determine the most economic disk setup for migrating a mail environment from an oversized storage system to a new storage environment using 7.2k 1TB drives with RAID 6. The document outlines key metrics measured by BVQ including IOPS, read/write distribution, and caching hit rates. Using these facts in a spreadsheet calculation, the results determine that 48 disks would be needed to support the 2500 IOPS requirement and 40TB capacity, requiring fewer disks and costs than alternative scenarios without the detailed performance data.

1. Find most
economic
disk setup
with BVQ
Michael Pirker
Michael.Pirker@SVA.de
+49 151 180 25 26 00
Bsys2.pptx

2. Target for this presentation
• Target
• a mail environment has to be moved from an oversized 10k 300GB storage to a new
storage environment. The new environment shall use 7.2k 1TB drives with Raid 6.
• BVQ is already installed so we can measure IOPS, RW Distribution and caching to do
a most economic sizing
• We analyze the performance of all disks that are involved
• We can proof that 2500 IOPS are what we need
• It is already known that R/W distribution is 55% Read
• The diagram shows a constant read cache hit rate of 90%
• The diagram shows a constant write cache hit rate (overwite in cache) of 15%
SVC will put all write data on the cache but 15% of this data will be overwritten before
destaging happens. These IOPS will never affect the disk.
• Safety Margins We see a transfer rates which will improve write penalties for raid 6. ánd we
use a conservative IO estimation for 7k drives. We do not take in account that the storage
system may further improve IO behavior with of own caching
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3. Select Volumes for performance analysis
Make use of the BVQ Accounting Package
Create a Volume Group of all Volumes that
belong to the mail system
Analyze the Volume Group now
Without Accounting Package you can select all
volume by search.
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4. Facts measured to support calculation
• Requested
• 40 TB Capacity
• 2500 IOPS Cache
Hit Read
• Facts from Chart (4 work days) Transfer
• 55% RW Distribution Size RW
• 90% Cache Hit Read
• 15% Cache Hit Write IOPS
RW
• Big Transfer size improves Cache
“Write Penalty” for Raid 6 Hit Write
(Full Striped Writes)
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5. Results with Spreadsheet
• Target IOPS 2500 IOPS
• RW Distribution: was measured before. Splits IOPS in
R/W
• Cache Hit Read: Reduces read IOPS with measured
Cache Hit Rate
• Cache Hit Write Reduces write IOPS (Overwrite in
Cache ) with measured Cache Hit Rate
• IOPS eff. is sum of read IOPS
and write IOPS
• The number of disks are now calculated with this formula
Result is 48 Disks with 7.2kRPM
Good fit because we need 40TB
capacity
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6. What makes this result particularly valuable?
• calculated based on facts
decreased the number of needed Disks dramatically
• most economic result
• minimum of costly safety margin
Other scenarios without knowledge about facts
We assume Raid 6 and 50% read and 70% cache hit for read
IOPSeff = 1625 72 Disks
We assume Raid 6 and nothing more
IOPSeff = 2500 201 Disks
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7. BVQ in the www
• BVQ Website
http://www.bvq-software.com/ (still German will change to English until latest Feb 25. 2013)
http://www.bvq-software.de/ (German)
http://bvqwiki.sva.de (technical wiki with download – international)
• BVQ Videos on YouTube
http://www.youtube.com/user/SVAGmbH
• SVA Webseite von SVA GmbH
http://www.sva.de/
Internationale Webseiten
• Developer Works Documents and Presentations
https://www.ibm.com/developerworks/mydeveloperworks/...
http://tinyurl.com/BVQ-Documents
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