EMC Celerra Manager Makes Customizing Storage Pool Layouts Easy. Applied Technology

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1 EMC Celerra Manager Makes Customizing Storage Pool Layouts Easy Applied Technology Abstract This white paper highlights a new EMC Celerra feature that simplifies the process of creating specific custom storage pool configurations. This paper explains the benefits of using this feature. It also describes several use cases for user-defined storage pools, and how to configure them. June 2010

2 Copyright 2010 EMC Corporation. All rights reserved. EMC believes the information in this publication is accurate as of its publication date. The information is subject to change without notice. THE INFORMATION IN THIS PUBLICATION IS PROVIDED AS IS. EMC CORPORATION MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WITH RESPECT TO THE INFORMATION IN THIS PUBLICATION, AND SPECIFICALLY DISCLAIMS IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Use, copying, and distribution of any EMC software described in this publication requires an applicable software license. For the most up-to-date listing of EMC product names, see EMC Corporation Trademarks on EMC.com All other trademarks used herein are the property of their respective owners. Part Number: h7260 Applied Technology 2

3 Table of Contents Executive summary... 4 Introduction... 5 Automatic Volume Management... 7 Use cases for user-defined storage pools... 9 Creating user defined storage pools...14 Conclusion...16 References...17 Applied Technology 3

4 Executive summary Business case Celerra Manager uses the Automatic Volume Manager (AVM) technology to create striped and concatenated groups, or volumes of LUNs balancing file systems for I/O loads across array resources such as disks and storage processors (SPs). For more control, storage administrators want to specify exactly how many LUNs of particular RAID types and drive types will be used for certain NAS file systems. Celerra has always offered a way to achieve this, but it was a manual process using a complicated command line interface (CLI), which tends to be error-prone. Implementation specialists and storage administrators want an easier and more reliable way to create custom user-defined storage pools for more predictable NAS file system performance. Product solution Celerra NAS version introduces a new feature in Celerra Manager that empowers administrators with the ability to create custom user-defined storage pools. Specifically, NAS administrators can create modified versions of the system-defined storage pools stipulating the number of stripe members (LUNs in the stripe) and the stripe size. This can now be done from the Celerra Manager graphic user interface (GUI). Applied Technology 4

5 Introduction Purpose This paper describes several common use cases in storage pool management and how they can be addressed by creating user-defined storage pools to match the needs of each use case. It also explains the procedure to create custom user-defined storage pools by size using Celerra Manager. Scope The paper assumes basic familiarity with Celerra Manager and AVM technology. Audience This paper is intended for customers including IT planners, storage architects, and administrators involved in managing, operating, or designing an EMC networked storage environment. Terminology Automatic Volume Management (AVM) A feature of the Celerra Network Server that creates and manages volumes automatically without manual volume management by an administrator. AVM organizes volumes into storage pools that can be allocated to file systems. file system Method of cataloging and managing the files and directories on a storage system. Network File System (NFS) Distributed file system providing transparent access to remote file systems. NFS allows all network systems to share a single copy of a directory. stripe volume An arrangement of volumes that appear as a single volume. A stripe volume allows stripe units that cut across the volume and are addressed in an interlaced manner. Stripe volumes make load balancing possible. storage pool The AVM feature organizes available disk volumes into groups called storage pools. Storage pools are used to allocate available storage to Celerra file systems. Storage pools can be created automatically by AVM or manually by the user. system-defined pool or system pool Predefined AVM storage pools that are set up to easily manage both storage volume structures and file system provisioning using AVM. user-defined pool or user pool User-created storage pools contain volumes that are manually added. They provide an appropriate option for users who want control on their storage volume structures while still using the automated file system provisioning functionality of AVM to provision file systems from the user-defined storage pools. Applied Technology 5

6 volume A block I/O device. On a Celerra system, a virtual disk into which a file system, database management system, or other applications place data. A volume can be a single disk partition or multiple partitions on one or more physical drives. There are many types of volumes such as metavolumes, stripe volumes, slice volumes, pool volumes, and disk volumes. Applied Technology 6

7 Automatic Volume Management Introduction to AVM Celerra offers many possible combinations to create a file system. However, AVM provides the greatest simplicity and ease of use while optimizing storage configurations for generic file system performance and availability. AVM automates volume creation and management, eliminating the need to manually create stripes, slices or metavolumes. It allows users to create and expand file systems without the need to create and manage the underlying volumes. AVM is storage-system independent and supports existing requirements for automatic storage allocation. Storage pool A storage pool is a container for one or more member volumes. All storage pools have attributes, some of which are modifiable. There are two types of storage pools. System-defined User-defined Understanding how AVM storage pools work enables us to determine whether system-defined storage pools or user-defined storage pools, or both, are appropriate for the environment. System-defined storage pools System-defined storage pools are predefined and available with Celerra Network Server. These predefined storage pools cannot be created or deleted because they are set up to manage volumes and file systems easily. AVM controls the allocation of storage to a file system when they are created by allocating space from a system-defined storage pool. System-defined storage pools are dynamic by default. The AVM feature adds and removes volumes automatically from the storage pool as and when required. Administrators can modify the attribute to disable this dynamic behavior. Limitations of system pools The following are the limitations of system pools: Some customer environments require more user control than what system-defined storage pools offer. One way for administrators to have more control is to create their own storage pools and define the attributes for the storage pools. Applications requiring precise placement of file systems on particular disks or on particular locations on specific disks is not possible. System pools provide less control over storage allocation and management. System-defined CLARiiON storage pools use all free disk volumes before maximizing the use of the partially used volumes. Databases such as Exchange and SQL Server make use of user-defined storage pools to gain better performance. Creation of Exchange databases Applied Technology 7

8 requires striping across metavolumes prior to the creation of user-defined pools. This flexibility of creating volumes is not available with system-defined pools. User-defined storage pools prior to NAS AVM user-defined storage pools allow more control over how the storage is allocated to file systems. Administrators can create a storage pool, and choose and add volumes to it either by manually selecting and building the volume structure or by auto-selection. They can expand the new volumes when required, or remove the volumes when they are no longer required in the storage pool. Auto-selection is performed by selecting disk attributes such as a minimum size and system pool. With auto-selection, whole disk volumes are taken from the volumes available in the system pool and placed in the user pool according to the selected stripe options. The auto-selection uses the same AVM algorithm that selects the disk volumes to stripe in a system pool. When extending a user-defined storage pool, AVM references the last pool member s volume structure and makes the best effort to keep the underlying volume structures consistent. User-defined storage pools are not dynamic, and require administrators to explicitly add and remove volumes manually. Limitations of user-defined pools prior to NAS The following are the limitations of user-defined pools prior to the NAS version: User-defined pools can be created either empty or with a list of volumes (disk/slice/meta) but not by size. The MPFS feature can give better performance with a higher stripe size. Creating user-defined storage pools with a 256K stripe size can yield better results. Stripe size cannot be modified with these storage pools. User-defined storage pools in NAS or later versions In NAS versions or later, user-defined storage pools can be created not only by volume but also with a size and a system pool template, optionally specifying the number of stripe members and a stripe size. Userdefined storage pools can be striped across a maximum of eight volumes with a higher stripe size of 256 KB whereas a system pool can stripe across only four volumes. The following are the advantages of user-defined storage pools in NAS or later versions: Stripe size and number of stripe volumes are modifiable Provides more control on storage allocation and management File system can be spanned across a maximum of eight disk volumes Applied Technology 8

9 Use cases for user-defined storage pools VMware use case A use case was developed to test the performance of user-defined storage pools in a VMware environment. The performance was tested for systemdefined storage pools with a default stripe size and user-defined storage pools with default and maximum stripe sizes. A small file system was created out of a large volume from system-defined and user-defined storage pools. This file system was hosted on a VMware environment as a VMware vstorage Virtual Machine File System (VMFS) volume and virtual machines were created. Tests were conducted to compare the performance of systemdefined and user-defined storage pools. System-defined storage pools created the file system by striping across only four volumes as shown in the following storage layout diagram. With the user-defined storage pools, the file system was striped across eight volumes as shown in the following storage layout diagram. Applied Technology 9

10 Performance comparison This environment was tested with different I/O profiles. The following graph compares the throughput of system-defined pools with user-defined pools for various I/O profiles. Applied Technology 10

11 The graph shows that throughput increases considerably in user-defined storage pools in complete Sequential Read and Mixed Read/Write environments. High throughput can be achieved with larger stripe sizes and more stripe volumes. The following graph shows the response times of system- and user-defined storage pools for various I/O profiles. Applied Technology 11

12 This graph shows that with lower response times, user-defined pools show better performance when compared to system pools. Exchange environment use case Provisioning storage for Microsoft Exchange, SQL, and Oracle environments to achieve the optimal performance requires a lot of configuration steps and some of those have to be done from the CLI. Any manual errors might degrade application performance. User-defined storage pools offer administrators the flexibility to provision with more control over how storage is aggregated to achieve balanced performance, high availability, and ease of use. The following figure shows a typical Exchange environment. Applied Technology 12

13 Based on EMC best practices, the following steps are required to create storage pools for the DB file system: 1. Load balancing the LUNs across storage processors (SPs) 2. Creating the metavolumes 3. Striping the metavolumes Instead of performing three steps, user-defined storage pools can be created in a single step through the GUI by specifying the number of stripe members and by selecting the system pool template. This takes care of the creation of volumes underneath. User-defined storage pools are easy to use and reduces the requirement for manual efforts required, which in turn reduces manual errors. Applied Technology 13

14 Creating user-defined storage pools Introduction This section provides details about the creation of user-defined storage pools using Celerra Manager. Create userdefined storage pool To create a user-defined storage pool, complete the following steps: 1. Log in to the Celerra Manager. 2. Navigate to Celerras>Celerra Name>Storage>Pools in the left pane. The Storage Pools page appears. 3. Click New. The New Storage Pool page appears. 4. Enter the following details in the New Storage Pool page: From the Template Pool drop-down list, select the storage pool to use that has system-defined storage pools with space available. In the Minimum Pool Size (MB) box, type the minimum size for this user pool. The actual user pool size may be much larger than what is specified because the entire disk volumes will be taken. In the Stripe Size (KB) box, type the stripe depth in multiples of 8 kilobytes. The recommended size is 32 KB, which is the default for most system pools. The recommended size for MPFSi and MPFS environments is 256 KB. In the Number of Stripe Members field, type the number of members needed in the stripe. The minimum value is 2. The recommended value for the specified pool appears in this field when the Template Pool option is changed. The recommended number of stripe members for most pools is 4. Click OK. Applied Technology 14

15 After the successful creation of a storage pool, the storage pool appears in the storage pool list with a confirmation message as shown in the following figure. Applied Technology 15

16 Conclusion Summary User-defined storage pools can be configured in Celerra Manager based on the stripe size and number of stripe volumes. This is a new feature in Celerra that improves AVM capabilities and provides flexibility to create storage pools. This feature customizes wider stripes, thereby offering more control on how the file system is placed on the disk volumes. It is also easy to use because the volumes are managed using the GUI. Applied Technology 16

17 References Product documentation The following documents available on Powerlink provide more information: Celerra Manager Online Help System Managing Celerra Volumes and File Systems with Automatic Volume Management Applied Technology 17