VMax Session 1

Symmetrix VMAX Training Summary (1 of 4)

A few months back I attended a Symmetrix VMAX training class. Afterwards I wrote up a document

summarizing some of the training and adding a bit of research into things that weren’t explained in depth

as I would have liked.

Symmetrix VMAX Training Summary (1 of 4)•




Architecture

A Symmetrix VMAX system is made up of “engines” and scales from 1 to 8 engines. Each engine is made

up of 2 “directors” and can support up to 360 drives per director. Each director consists of front end ports,

back end ports, 4 quad cord CPUs and 128 GB of memory. Cache in a VMAX system is shared globally

across all engines. Each engine is connected together by what is called a Virtual Matrix Fabric. The

interconnect technology inside this Virtual Matrix Fabrix is called RapidIO.

The Symmetrix system supports both mainframe and open systems hosts. The term “open systems” comes

from the 1980′s when mainframe systems started competing with Unix systems. Those Unix systems were

marketed as “open” because they featured standard APIs, and third party developed software was

encouraged. Verses “closed” mainframe systems, which the mainframe manufacturer made both physical

peripherals and software exclusively. During this time closed systems were more popular and big

companies like IBM resisted the “open” trend for many years.

The Symmetrix supports two different types of device emulation. A Count Key Data (CKD) device is used by

z/OS mainframe systems while Fixed Block Architecture (FBA) devices are used by open systems. CKD

allows the storage of variable sized blocks of data and allows searching by a key value, while FBA uses

fixed size blocks, usually 512 bytes. Faster CPUs, memory, and buses have somewhat nullified the

advantages of CKD. And FBA is a simpler architecture and in some applications offered faster throughput.

Posted by Eric on March 2, 2012 Leave a comment (10)Go to comments

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Symmetrix logical volumes are equivalent to what the industry refers to as a LUN, logical unit number.

Inside the EMC Symmetrix world, LUNs are referred to as a Symmetrix device or a Symmetrix logical

volume. When you create a device on a VMAX you specify the size and a protection level. The software that

runs the storage array, called Enginuity, intelligently chooses the physical disks out of the specified disk

group that will make up that device. Each slice of that device that is on a physical disk is called a hyper

volume. For example, provisioning a 500 GB RAID 5 device with 7+1 protection would cause the VMAX to

go out and intelligently choose 8 disks that have available space to create a 72 GB hyper volume on each

disk. The largest device that a Symmetrix currently supports is 262,668 cylinders, or 240 GB (262,668 cyl *

960 KB/cyl). Also, the maximum number of hyper volumes per physical drive is 1024 as of Enginuity 5875.

In general fewer, larger hyper volumes will perform better than many smaller hyper volumes.

Common device types include

2-Way-Mir (AKA RAID -1), RAID-5, RAID-6•

TDEV (Thin devices), DLDEV (Diskless devices), VDEV (Virtual devices for TimeFinder/Snap)•

BCV (Business Continuance Volume) used for local replication like cloning and snapshots•

DATADEV, and SAVEDEV are devices used to create thin pools, and virtual devices respectively•

RDF (Remote Data Facility) used for replication to a second storage array•

I found it interesting that there is no specific RAID 10 device type. To achieve something comparable you

would create multiple 2-Way-Mir devices and stripe them together in a meta device.

A meta device is simply multiple devices combined together to form a single device. The devices can be

combined in two ways, striped, or concatenated. Meta devices are needed if you want to create a device

that is large than the max size of 240 GB. Meta devices require a device to act as a meta head. You then

add devices to the head member. This is because the head member contains information about all the

other meta members so it can sometimes be a source of performance issues.

Generally a striped meta will perform better than a concatenated meta. However, care has to be taken

when creating a striped meta device so that no two meta member hyper volumes share the same physical

spindles. In virtual provisioning environments EMC recommends concatenated meta devices however when

using synchronous replication, striped meta volumes should be used based on our experience.

The VMAX supports up to 255 member meta volumes. Meta volumes with a number of members equaling

powers of 2 are preferred, for example, 4, 8, 16, or 32.

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10 Comments.Leave a comment ?



Symmetrix VMAX Training Summary (2 of 4) | ericstephani.com - pingback on March 2, 2012 at 11:24 am

Symmetrix VMAX Training Summary (4 of 4) | ericstephani.com - pingback on March 2, 2012 at 12:50 pm

Symmetrix VMAX Training Summary (3 of 4) | ericstephani.com - pingback on March 2, 2012 at 12:51 pm

Faisal Ghulam April 18, 2012 at 3:54 pm

Hi,

Can you have training or study material regarding this.

Eric April 18, 2012 at 9:29 pm

These are my own notes from the training class that I attended.

Ravi June 17, 2012 at 1:34 am

Hi eric, wonderful way of presenting. I wrote on several topics before and I can say I have to learn lot more things from you. I definitely see the home work you did to give an high level over view of VMAX like this!

javed shaikh July 14, 2012 at 1:58 am

hi eric, In your post u mentioned if we need 500 gb raid 5 (7+1) devices. then the vmax will select 72 gb hypers on 8 physical disks . But what if we have hypers of 8 gb,16 gb, 32 gb or more than 72 gb what will happen on that case

Thanks& regards Javed

javed shaikh July 14, 2012 at 2:14 am

would it be like 32 gb hypers on 16 physical disks

Roomi October 6, 2012 at 5:37 pm

your notes are awesome Eric, great piece of work , I really appreciate your effort . God bless you

Eric October 7, 2012 at 9:00 am

I am not sure. I haven’t been digging around at this level in a while, but I beleive you can not control the size of the hypers. I could be wrong.



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