Module 11 Multi-Member Groups Pools Thin Provisioning 25 Pages

7/28/2019 Module 11 Multi-Member Groups Pools Thin Provisioning 25 Pages

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PS Series supports Tiered Storage, which enables you to define multiple tiersor poolsofstorage in a single PS Series group (SAN). Tiered Storage provides administrators with greatercontrol over how disk resources are allocated. While online, volumes can be allocated andmoved between tiers of storage, providing high levels of service.

Some examples of Tiered Storage:

Meet cost-of-service needs. You can place data on the storage resource that isappropriate for the type of data and how it is being used. For example, Backupdata can be placed on RAID 50, Replication data can be placed on RAID 50and the Transaction logs can be placed on RAID 10.

Improve quality-of-service controls. For example, you can Isolateapplications such mail and databases from other applications and also separatedisaster recovery data from production data.

Set up technology-defined tiers. For example, you can set up tiers withcommon RAID levels or disk types or speeds.

Organize according to physical location. Because the SAN can spangeographic areas, servers can access storage that is physically close.

Segregate storage for different organizations. For example, you can isolateaccounting resources from engineering data in a single SAN.

You can create multiple tiers of storage within a single, multi-member PS Series groupby creating multiplestorage pools. Pools allow you to control where data is located.

Pools - A pool consists of one or more group members (PS Series arrays). At any one time, amember can be assigned to only one poolor storage tier. It is easy to assign a member to a

pool and also to move a member between pools, with no impact on data availability, providingadministrators with the flexibility needed to meet their business needs.

Volumes are also assigned to a pool and can be easily moved between pools, with no impact onavailability. In addition, automatic data placement and load balancing occurs within a pool,

based on the overall workload of the storage hardware resources within the pool.

l EqualLogic PS Series Storage Solution and

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When the first PS Series array member is initialized and added to the group, it is added to the

default pool.

If it is added using the CLI, a RAID type must also be applied to the array before anycapacity is allocated to the group.

When a second member is added to the group, it can be added to the existing pool or to a newpool.

When the member is initialized, none of the available storage capacity of that member

is allocated to the group/pool because a RAID level has not been applied to the newmember.

Once the RAID has been specified, the new members storage capacity will be

allocated to the pool it was added to.

A single pool can have multiple members in the pool. Each member can be a

different RAID type as shown in the diagram.

Here you can have a PS6000X as a RAID 50 and a PS6000XV as a RAID 10and a PS6000E as a RAID 5 all within the same pool. The volumes will move

to the appropriate member based on I/O characteristics.

It is always recommended in a mixed spindle speed environment that you usepooling to separate the slower SATA arrays from the faster SAS arrays

If you have multiple members with different RAID types within a single pool:

Volumes will move automatically between members based on the I/O characteristicsof the volume. The I/O is based on the RAID type, if the volume preferenceis set to

Automatic.

Volumes can be associated with a particular member, based on RAID type, by settingvolume preferenceon the volume to the desired RAID type.

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Volume Preference

The ability to identify a particular RAID type to a specified volume

Automatic (default) preference allows the volume to be monitored over an

extensive period of time (approximately 12 -15 days). Based on the I/O

characteristics, move the volume to the appropriate RAID type indicated bythe monitored I/O characteristics.

Choices

Automatic (default)

RAID 50

RAID 10

RAID 5

RAID 6


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- Hot and cold page swapping is introduced within the 5.1 version of the firmware

- This decreases member latency

- A hot page is defined as a page that is currently being written to or that has recently been written to.

- A cold page is defined as a page that has not been written to.

- Member latencies are evaluated every two minutes.


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- The Hot and cold page swapping algorithm is very similar to the Page swapping

that occurs within the hybrid model array.(PS6000 XVS & PS6010 XVS)

- Hot and cold page swapping will not create additional volume slices as this

violates the capacity balancer rules.

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- The members that are identified within the swap is defined by the member latency

and the Hardware Score.

- The Hardware Score is based upon the hardware of the member, for example,

SATA vs. SAS drives.


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Tiered storage with multiple pools

Tiered storage with multiple pools allows:

Separation of storage based on customer requirements

Control of separate storage

Appears like virtual SAN islands

Tiered storage with multiple pools prevents:

Volumes from using available capacity in another pool. A volume is

restricted to the pool it resides in.

Automatic movement of volume using volume preferences only

happens within a pool and not between pools

PS Storage arrays are added to the group and to a pool

When the array is added, it can be added to an existing or new pool

As of firmware version 3.2.x, pools can be merged. Prior to that, pool merging was manual.


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Dell EqualLogic delivers automation with fine-grain control

Results in easy online operations

STEP 1: Categorize data needs and business applications into

logical groups that require similar service levels:

Departmental

Application

Physical

STEP 2: Segment and assign storage arrays to defined pools

Tier storage pools by disk type and RAID type


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To create a storage pool:

Select the activities panel of the group summary window and then select create a

storage pool.

Select the storage pool icon and the create a storage pool option.

When the create storage pool dialog box appears, specify a pool name and optionaldescription then click OK.

Assigning members to storage pools

Expand members and select the member name.

In the Activities panel, click modify member settings.

The modify member settings dialog box appears displaying the available pools and thecapacity and free space in each pool.

Select the pool for the member and click OK.

If multiple pools are available, specify the pool when first configuring the RAID policyfor the member.

If not available, the member will be assigned to the default pool.

Assigning volumes to pools:

In the leftmost panel, expand volumes and select the volume name.

In the activities panel, click modify member settings.

The modify volume settings dialog box appears displaying the available pools and thespace available in each pool.


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A pool has storage capacity only when a member has been added to it

If a member is moved from one pool to another, then the volumes remain in the

original pool and the member and its storage capacity are moved to the new pool.

The member can only move if the member or members remaining in the original poolhave the storage capacity to handle all of the volumes.

To create a storage pool:

Select the activities panel of the group summary window and then select create a

storage pool.

Select the storage pool icon and the create a storage pool option.

The create storage pool dialog box appears. Specify a pool name and optionaldescription and click OK.

Assigning members to storage pools:

Expand members and select the member name.


The modify member settings dialog box appears displaying the available pools and the

capacity and free space in each pool.

Select the pool for the member and click OK.

If multiple pools are available, you can specify the pool when first configuring theRAID policy for the member.

If multiple pools are not available, the member will be assigned to the default pool.

Assigning volumes to pools:

In the leftmost panel, expand volumes and select the volume name.


The modify volume settings dialog box appears displaying the available pools and thespace available in each pool.


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Multiple pools per group

A pool can be merged into another pool

Select the pool to be merged

Identify the destination pool

Move the source pools capacity and volumes to the destination poolDelete the old pool


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Each pool can be managed by a pool administrator user while the group can be

managed by the grpadmin user


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Storage/volume provisioning is usually comprised of a number of factors. In most cases this causestension between storage and application groups and often contributes to poor capacity utilization within

the SAN.When done correctly, provisioning results in storage that performs well and scales without

disruption.When provisioning isn't done correctly, application performance can degrade, security is

compromised, scalability is inhibited and capacity utilization is low, resulting in wasted storagespace

Today, excessive amounts of capacity are over-allocated to applications to meet volatile growth

expectations, assure service levels, and avoid future upgrade complexity. Enterprise users estimate thatused allocated capacity is only 25%-35% of total allocated capacitya monumental waste of capital and

related operating expense. The problem of allocated-but-unused capacity is not solved by physicalstorage networking since this capacity is already logically assigned to and owned by applications 1

In general, experts recommend provisioning LUNs at least 30% to 50% larger than the expectedsize. 2

The operating system determines how flexible it is in provisioning additional storage to meet the needs of

the application

If your OS supports online expansion expand the file system on the server

Two-step process:

make the volume bigger

expand the file system

What happens if you have 100 servers?What if your OS does not support online file system expansion?

Plan downtime

create new volume (bigger);

copy data

reconfigure applications to use new volume

Test

delete old volume

What happens if you have 100 servers?

2 The Right Way to Provision Storage, Alan Radding, 26 Oct 2006 | Storage Magazine

1 Byte and Switch June 2003


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Storage provisioning is the process of logically carving up physical disk space to meet anorganization's need for storage capacity, performance, security and efficiency.

Storage provisioning encompasses the assignment of servers/hosts to appropriate storage,specifying network paths between hosts and storage, and setting up appropriate access controlto ensure access by the appropriate servers.

Thin provisioning allows space to be easily allocated to servers on a just-enough and just-in-timebasis.

Thin provisioning allows administrators to maintain a single free space buffer pool toservice the data growth requirements of all applications.

This avoids poor utilization rates, often as low as 50%, that occur on traditional storagearrays. This happens when large pools of storage capacity are allocated to individualapplications but remain unused (i.e. not written to).

This traditional model is often called fat provisioning.


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With thin provisioning, storage capacity utilization efficiency can be automaticallydriven toward 100% without heavy administrative overhead. Organizations canpurchase less storage capacity up front, defer storage capacity upgrades in line withactual business usage, and save operating costs (electricity and floor space)associated with keeping unused disk capacity spinning.

Previously, systems generally required large amounts of storage to bephysically pre-allocated because of the complexity and impact of growingvolume space. Thin provisioning is sometimes also an enabler for Over-Allocation, also known as Over-Subscription.

Over-Allocation is a mechanism that allows server applications to beallocated more storage capacity than has been physically reserved on thestorage array itself. This allows leeway in growth of application storagevolumes without having to accurately predict which volumes will grow byhow much. Physical storage capacity on the array is only dedicated whendata is actually written by the application, not when the storage volume isinitially allocated.


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Snapshot reserve, local replication reserve, and replica reserve for a volume are all based

on the current volume reserve not the reported volume size.

Thin-provisioned volumes are useful in situations where a volume is likely to grow overtime but which does not need immediate, guaranteed access to that entire amount of

space.

Configuring a thin-provisioned volume reduces the administrator overhead involved in

manually growing a volume when the need arises.

When you receive an alert that the volume has consumed space up to the in-use warninglevel you specified, you can examine the available space in the group or pool and add morespace for the volumes future growth.

If the volume reaches the Maximum in-use marker then the volume will go off line and no

longer allow you to write to the volume until additional space is allocated to the volume

A regular, non-thin provisioned volume is one that has been allocated exactly the amountof space specified when it was created. Its size is fixed.

These volumes do not grow over time but can be increased, decreased, or converted to

thin-provisioned volumes as needed.


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Documents

Module 11 Multi-Member Groups Pools Thin Provisioning 25 Pages