how to reduce SVC / Storwize storage costs with proper planning

1. BVQ Use Case: Cost
effective Storage planning
Michael Pirker Pirker SVA GmbH

2. Use Case Target
A 40 TB mail system has to be moved from an oversized 10k, 300GB storage to
a new storage environment with lower cost 7.2k, 1TB disk drives and Raid 6. The
question is how many disks are needed in the new 7.2k disk arrays to deliver the
same performance as before.
With BVQ we are able to analyze the aggregated performance values of all
Volumes, which make up the mail system.
Fact based knowledge about Workload Picture 2 (known by measurement)
• 40TB capacity is needed
• the mail system consumes 2500 IOPS
• the R/W distribution is 55% read
• The diagram shows a constant read cache hit rate of 90% and write cache
hit rate (overwrite in cache) of 15%. This will reduce the IOPS on Disk
heavily.
• Safety Margins:
We see big transfer rates, which will improve write penalties for raid 6. And
we use additionally a conservative IO estimation for 7k drives. We also do
not take in account that the storage system behind SVC may further
improve IO behavior with own caching.
Picture 1 BVQ Treemap with Cost Centers and Applications: With the BVQ Accounting Package allows
grouping Volumes and adding them to applications or even costing centers. A good starting point for our
investigation because we are not only interested in single volumes but in all volumes belonging to the mail
system. We now can start a performance analysis where all IOPS, Transfer Sizes and Cache Values are
aggregated into single curves.
-1-

3. Picture 2: BVQ Performance View screen: You see the aggregated Values of IOPS, transfer size, cache hit
read and cache hit write of all volumes. It is obvious that the backup IO patterns overnight are completely
different from the business hours. But in both cases we have very stable cache hit results with 90% cache hit
read and 15% cache hit write (overwrite in cache).
Picture 3: IOPS Calculations: This is a spreadsheet that I use to calculate the numbers of disks needed for
specific IOPS scenarios with cache and RW Distribution. When we start with the 2500 IOPS needed and
subtract cache hits from read and, write we end with only 1094 effective IOPS that have to be covered from
the disks. We use the formula and more or less conservative IOPS/spindle constants and a RAID penalty and
come to the result of 48 spindles to cover the 1094 IOPSeff
-2-

4. What makes this result particularly valuable?
With this fact based approach we are able to find the most economic solution to
meet the performance target. We reduce today’s hardware purchasing costs and
tomorrows follow-up costs because we need less spindles, enclosures, systems,
floor space, power, cooling.
Ideas to improve even more!
• Challenge backup duration – is this critical – if not we can reduce the
needed IOPS down to 2000 IOPS or even less. With 2000 IOPS we would
end with only 38 disks for performance – please keep in mind that we
need 40TB so we could decide for 2TB disk drives.
My guess for our special example would be – it is critical because when
you look into the transfer sizes we see that backup starts at 9pm and
finishes approx. 6am
• Have a look to Easy Tier –analyze on single disks to check whether we
find IOP patterns that will be handled preferred by Easy Tier.
Other scenarios without knowledge about facts
Without fact based knowledge about RW distribution and caches you are forced
to work with assumptions.
• Lets assume Raid 6 and 50% read and 70% cache hit for read
IOPSeff = 1625 72 Disks
• Lets assume Raid 6 and nothing more
IOPSeff = 2500 201 Disks
-3-

5. BVQ Web Pages
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)
• BVQ Videos on YouTube
http://www.youtube.com/user/SVAGmbH
• SVA Website 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
If you are interested in BVQ a demo or a Performance Analysis then please
contact bvq@sva.de
BVQ is a product from SVA System Vertrieb Alexander GmbH
-4-