Tape Drive Performance Tuning on Solaris 10 Systems

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Performance Degradation with MPxIO and Symmetric Devices (Sun Storedge[TM] 99xx/3510 and Sun Fire Servers

DescriptionSequential I/O performance degradation of up to 700% has been seen with Symetric devices connected to the host running Sun StorEdge[TM] Traffic Manager Software (MPxIO) with round-robin load balancing.

Steps to Follow
The round-robin method is the default load balancing method when MPxIO is
enabled. This method works fine with Asymetric FC (Fibre Channel) devices such as Sun StorEdge[TM] T3, which present LUNs to the host in Active/Passive mode.
The method works counterproductive with Symetric FC Devices like the
internal drives of Sun Fire[TM] v880, v1280 or v480, the Sun Storedge[TM] A5x00, 3510, or 99xx array (the 99xx array has a pre-fetch cache alogorithm built into it).

The root cause of the problem is due to the way the MPxIO round-robin
method distributes the I/O on 2 or more channels. In the case of an
internal disk, or any FC devices in a arbitrated loop, the I/O hits the
disk directly from one channel per command. The disk completes the I/O and
gets a request from the other channel. This causes the disk to spin
(rotational delay) before servicing the request. The length of delay will
vary depending on the number of commands being issued in each path and is
very visible with the Sequential I/O. The problem is more visible with
Veritas Volume Manager or Solaris Volume Manager, which has stripped
volumes with the 16K-interlace factor. This causes an even higher number of
commands that need to be sent down to a specific disk, causing high-service
times for each command.

The Storedge 99xx array has its own pre-fetch cache algorithm, which in
some cases, may cause performance degradation.
The solution is a new method of load-balancing; the "logical block" method.
This method uses a region size (specified in the conf file of 16, 32 ....),
then routes all I/Os, starting within a certain 64K range, through the
same path. I/Os that start within other 64K ranges on the disk will be
routed through a different path. This way, the disk can catch the stream
I/O better, which improves the performance.

Below are basic changes in the scsi_vhci.conf for using the "logical block"
method. 1004918.1 describes the new load balancing method in
detail.

This is provided through the new property,
"device-type-mpxio-options-list".

device-type-mpxio-options-list=
"device-type=SUN     SENA", "load-balance-options=logical-block-options";
"device-type=SEAGATE ST373307FSUN72G",
"load-balance-options=logical-block-options1",
"device-type=HITACHI OPEN-L*4    -SUN",
"load-balance-options=logical-block-options2",
"device-type=SUN     T300", "load-balance-options=logical-block-options1";
logical-block-options="load-balance=logical-block",  "region-size=15";
logical-block-options1="load-balance=logical-block", "region-size=18";
logical-block-options2="load-balance=logical-block", "region-size=32";

Note: The Product ID in the device-type string should start at the "9th"
character. Otherwise, it will use the default round-robin load balancing
method.

This logical-block method is available beginning with SAN 4.4
Add the Below entry in /kernel/drv/scsi_vhci.conf  to enable logical-block

device-type-mpxio-options-list =
"device-type=HITACHI OPEN-V      -SUN",
"load-balance-options=logical-block-options";
logical-block-options="load-balance=logical-block", "region-size=18";

Amazon EC2 pricing models

Cloud computing is changing the way IT resources are utilized. Now a days cloud computing is one of the Innovated technology platform & emerging trend for IT industry & certainly not limited to it.

Cloud computing is a simple idea, but it can have a huge impact on business.

There are many vendors for enabling/providing cloud computing solutions like Amazon, VMWare, Rackspace and many more.

Today we will focus on Amazon EC2 (Amazon Elastic Compute Cloud).

Amazon is a leading public cloud computing provider, AWS (Amazon Web Services) falls in the infrastructure as a service (IaaS) space, providing on demand service using virtual server instances with unique IP addresses and blocks of storage.

It's a news for me and may be for many of us that AWS opening a data center in Singapore to make its entry in the Asia Pacific region has created a lot of interest about Amazon Elastic Compute Cloud (Amazon EC2) in India.

So just to take a quick tour of AWS offerings - AWS provides various components/services like Amazon EC2, Amazon Simple Storage Service (Amazon S3), Amazon SimpleDB, Amazon Relational Database Service (Amazon RDS).

As AWS is stepping in to Asia Pacific region I'm very excited to know what will be the pricing model for their service offerings. So let's take a look at their pricing model.

Amazon EC2 pricing models follows a "pay-as-you-go" model (as in any other cloud computing model) however the flexibility is at it's par in case of Amazon EC2 pricing model.

When it comes to Amazon EC2 pricing models, the instances are grouped into three families:
1. Standard,
2. High-Memory
3. High-CPU.

Amazon EC2 pricing for each of these instances is as follows:

1. Standard Instances -- This model have memory to CPU ratios suitable for most general purpose applications. This Amazon EC2 pricing model ranges from $0.12 per hour to $ 0.96 per hour, for services running on Windows infrastructure. For infrastructure running on Linux and UNIX, Amazon EC2 pricing starts with $0.095 per hour to $0.76 per hour.

2. High-Memory instances -- This Amazon EC2 pricing model offers larger memory sizes for high throughput applications, including database and memory caching applications. This is priced at $ 0.62 per hour to $2.88 per hour for Windows based infrastructure. For Linux/UNIX based instances in this pricing model of Amazon EC2, prices range from $0.57 per hour to $2.68 per hour.

3. High-CPU instances: In this Amazon EC2 pricing model, proportionally more CPU resources are consumed than memory (RAM), and as a a result it targets compute-intensive applications. This Amazon EC2 suite has been priced at $0.29 per hour to $1.16 per hour for Windows based infrastructure. For Linux or UNIX based infrastructure, this Amazon EC2 pricing model charges from $0.19 per hour to $0.76 per hour.



When choosing Amazon EC2 pricing types, organizations should consider characteristics of their application with regards to resource utilization. Accordingly, they should select the optimal instance family and size.

Now we have understood the pricing model & now next question comes in heart is how about support model so here we go -

here are two AWS Premium Support offerings—Gold and Silver. The following is the breakup of the services.


Gold Support includes:


-Business day support (6 a.m. to 6 p.m.)
-24x7x365 coverage.
-One-on-one support via web-based ticketing system.
-One-on-one support via telephone.
-1 hour maximum response time for "Urgent issues".
-Guaranteed response time for non-urgent issues.
-Client-side diagnostic tools.
-Named support contacts.


Silver Support includes:


-Business day support (6 a.m. to 6 p.m.).
-One-on-one support via web-based ticketing system.
-Guaranteed response time for non-urgent issues.
-Client-side diagnostic tools.
-Named support contacts.

I hope it's worth knowing all this information as a IT Infrastructure professional.

Also as we all know pictures talks louder & who agree to it then here is a very good video for understanding cloud computing in simple language.

http://www.youtube.com/watch?v=XdBd14rjcs0

Hope this article helps...