Veritas Storage Foundation Intelligent Storage Provisioning 5.
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Contents Chapter 1 Introduction to ISP Basic concepts in ISP ............................................................................................. 8 About storage pools ....................................................................................... 8 About templates, capabilities and rules ...................................................11 About user templates ..................................................................................
6 Contents
Chapter 1 Introduction to ISP Intelligent Storage Provisioning (ISP) is a feature of Veritas Storage FoundationTM that provides new approaches to virtualizing network storage. ISP allows application volumes to be created from the available storage that adhere to a set of specified criteria. Using ISP simplifies and standardizes storage provisioning, allows the redundancy and performance characteristics to be preserved over time, and helps to eliminate human error when allocating storage to volumes.
8 Introduction to ISP Basic concepts in ISP Basic concepts in ISP Provisioning storage so that it can be used by applications involves: ■ Configuring the physical storage devices (disks and derived logical units). ■ Ensuring that the appropriate hosts can access the devices. ■ Aggregating the available storage capacity into virtual storage devices known as volumes. ■ Providing a method for applications to store and retrieve data on the volumes, such as through a file system or a database.
Introduction to ISP Basic concepts in ISP Figure 1-1 Traditional disk group in VxVM Disk group Initialized disks ISP extends this model by allowing the installation to enforce volume provisioning standards as defined in a set of templates. To create ISP volumes, you need to set up a storage pool within a VxVM disk group and associate the appropriate volume templates with the storage pool. This is illustrated in Figure 1-2.
10 Introduction to ISP Basic concepts in ISP Any traditional non-ISP volumes that you create in a disk group with a storage pool remain outside the storage pool. To create a storage pool within a disk group, use the vxpool create command and specify a storage pool definition that is appropriate for the kind of volumes that you wish to create. This sets up the storage pool and installs the correct templates in it.
Introduction to ISP Basic concepts in ISP For full details about the templates that are installed for each type of storage pool definition, see the Veritas Storage Foundation Intelligent Storage Provisioning Administrator’s Guide. Note: The first storage pool that is defined within a disk group is referred to as a data storage pool. All other storage pools that are subsequently defined within the same disk group are referred to as clone storage pools.
12 Introduction to ISP Solutions using ISP capability creates a volume with 2 mirrors by default, and has a parameter, nmirs, that you can use to specify a different number of mirrors. In addition to specifying the capabilities of a volume, templates can include storage selection rules that specify how to select the appropriate storage, and storage layout rules that define how volumes are to be created.
Chapter 2 Volume creation solutions Volumes that you create by using Intelligent Storage Provisioning (ISP) are similar to traditional non-ISP volumes that you create using the vxassist utility, but have the advantage that their intent is preserved and cannot accidentally be degraded. ISP volumes can be managed by using commands such as vxassist or vxvoladm, or by using the VEA client graphical user interface. In release 5.0 of VxVM, it is possible to use the vxassist command to create ISP volumes.
14 Volume creation solutions Using storage attribute tags with volumes be combined with a multipathing capability to provide resilience against the failure of one of the paths to an enclosure: # vxassist -g mydg -P mypool make strpvol 2g \ capability=’DataMirroring,MirrorsOnSeparateComponents,\ MultipathingThroughMultiplePaths’ If no storage can be allocated that fulfills the requested capability, the command fails.
Volume creation solutions Creating tagged volumes This sets the attribute tag Room on the disks (mydg01 through mydg08) with values that represent the physical location (room1 or room2). The following command uses the new attribute tag to create a mirrored volume that tolerates the failure of a single enclosure, where each enclosure is in a different room. This avoids single point of failure and ensures greater reliability.
16 Volume creation solutions Using user templates to simplify volume creation mirrors in each volume should be allocated on separate enclosures, and that enclosure ENC1 should not be used at all.
Volume creation solutions Using user templates to simplify volume creation 4 Verify that all volumes in the disk group conform to the template, pool, volume group, and user-specified rules.
18 Volume creation solutions Using user templates to simplify volume creation
Chapter 3 Tiered storage solutions The typical requirements of enterprise-level storage management are to store and reliably maintain data from a number of different sources, such as inventory, customer, billing, business intelligence and personnel records. Such data is usually stored in file systems on several host systems.
20 Tiered storage solutions Policies for storage tiers Cost Benefit Application Low High Archive data, such as historical customer and account records, which needs to be accessible but is not used heavily. These files are stored in mid-range to low-end storage arrays with fast, reliable network connections. Low Low Data that has little impact on an enterprise’s business. These files are stored on low-cost media, such as tape, with little consideration given to performance.
Tiered storage solutions Policies for storage tiers The following table shows the typical factors that can be taken into account when implementing policies for storage tiers. Factor Description Availability Some files are more valuable than others to an enterprise. For example, losing a day's business transactions is significant but probably survivable. Losing quarterly or annual closing figures, on the other hand, might be catastrophic.
22 Tiered storage solutions Policies for storage tiers days. Figure 3-1 illustrates such a configuration where a file system has been created on a volume set that is composed of volumes that have been tagged with tier values that correspond to the cost of the storage from which they have been created.
Tiered storage solutions Setting up tiered storage using ISP volumes Setting up tiered storage using ISP volumes To establish a storage tier using ISP volumes in a volume set 1 Use the vxdiskadm command or the GUI to create the disk group that will be used to hold the tiered volumes and the volume set to which they will be added. Add all the disks that are required to this disk group. 2 Define the rules to categorize the disks into storage tiers.
24 Tiered storage solutions Setting up tiered storage using ISP volumes If you are creating many volumes at the same time, or you may need to repeat the procedure in the future, it is preferable to define the volumes to be created as a volume group in a definitions file, and then use the vxassist -M make command to read this and set up the volumes. For details, see “Creating multiple volumes” on page 15 and the Veritas Storage Foundation Intelligent Storage Provisioning Administrator’s Guide.
Chapter 4 Off-host processing solutions Veritas Volume Manager (VxVM) allows point-in-time copies of a volume’s data, or snapshots, to be processed by alternate hosts while an application continues to access the data in the volume. Off-host processing reduces downtime and allows you to implement the following activities: Data backup As the requirement for 24 x 7 availability becomes essential for many businesses, organizations cannot afford the downtime involved in backing up critical data offline.
26 Off-host processing solutions Implementing off-host processing solutions Database error recovery Logic errors caused by an administrator or an application program can compromise the integrity of a database. By restoring the database table files from a snapshot copy, the database can be recovered more quickly than by full restoration from tape or other backup media.
Off-host processing solutions Implementing off-host processing solutions Figure 4-1 Example implementation of off-host processing Primary host OHP host SCSI or Fibre Channel connectivity Disks containing primary volumes used to hold production databases or file systems Disks containing snapshot volumes used to implement off-host processing solutions Note: A volume snapshot represents the data that exists in a volume at a given point in time.
28 Off-host processing solutions Implementing off-host processing solutions The following sections describe how you can apply off-host processing to implement regular online backup of a volume in a private disk group, and to set up a replica of a production database for decision support. Two applications are outlined: ■ Implementing off-host online backup ■ Implementing decision support These applications use the Persistent FastResync feature of VxVM in conjunction with linked break-off snapshots.
Off-host processing solutions Implementing off-host processing solutions 4 Create the snapshot volume, snapvol, by running the following command on the primary host: # vxsnap -g volumedg make \ source=volume/snapvol=snapvol/snapdg=snapvoldg If a database spans more than one volume, you can specify all the volumes and their snapshot volumes using one command, as shown in this example: # vxsnap -g dbasedg make \ source=vol1/snapvol=snapvol1/snapdg=sdg \ source=vol2/snapvol=snapvol2/snapdg=sdg \ source=vol3
30 Off-host processing solutions Implementing off-host processing solutions 13 On the primary host, reattach the snapshot volume to its original volume using the following command: # vxsnap -g snapvoldg reattach snapvol source=vol \ sourcedg=volumedg For example, to reattach the snapshot volumes svol1, svol2 and svol3: # vxsnap -g sdg reattach svol1 \ source=vol1 sourcedg=dbasedg \ svol2 source=vol2 sourcedg=dbasedg \ svol3 source=vol3 sourcedg=dbasedg You can use the vxsnap snapwait command to wait for s
Off-host processing solutions Implementing off-host processing solutions This step sets up the snapshot volumes, and starts tracking changes to the original volumes. When you are ready to create a replica database, proceed to step 4. 4 On the primary host, suspend updates to the volume that contains the database tables. The database may have a hot backup mode that allows you to do this by temporarily suspending writes to its tables.
32 Off-host processing solutions Implementing off-host processing solutions To resynchronize the snapshot volume’ s data with the primary database by refreshing the snapshot plexes from the original volume 1 On the OHP host, shut down the replica database, and use the following command to unmount the snapshot volume: # umount mount_point 2 On the OHP host, use the following command to deport the snapshot volume’s disk group: # vxdg deport snapvoldg 3 On the primary host, re-import the snapshot volume’
Chapter 5 Remote mirror solutions The Remote Mirror feature of the Storage Foundation software mirrors volumes at separate sites, which allows applications to be recovered at an alternate site in case of site failure. An enterprise can thus continue to function despite the loss of one site. This feature supports both non-ISP and ISP volumes. The solution presented below is intended to highlight how to implement the remote mirrors for ISP volumes.
34 Remote mirror solutions About Remote Mirror configurations Example of a two-site remote mirror configuration Figure 5-1 Site A Cluster Nodes Private Network Metropolitan or Wide Area Network Link (Fibre Channel or DWDM) Site B Cluster Nodes Fibre Channel Hubs/Switches Disk Enclosures Disk Enclosures For applications and services to function correctly at a site when other sites have become inaccessible, at least one complete plex of each volume must be configured at each site (site-based alloc
Remote mirror solutions About Remote Mirror configurations Site-consistent volume with two plexes at each of two sites Figure 5-2 Site A Disk Group Site B Volume V Plex P1 Plex P2 Plex P3 Plex P4 Although they are not shown in this figure, DCO log volumes are also mirrored across sites, and disk group configuration copies are distributed across sites. The site consistency of a volume is ensured by detaching a site when its last complete plex fails at that site.
36 Remote mirror solutions About Remote Mirror configurations To check which disks are registered to a site, use this form of the vxdisk command: # vxdisk listtag Note: All the disks in a disk group must be registered to one of the sites before you can set the siteconsistent attribute on the disk group in the next step. 3 Turn on the site-based allocation requirement for a site that is registered to a disk group.
Remote mirror solutions About Remote Mirror configurations Making an existing disk group site consistent To make an existing disk group site consistent 1 Ensure that the disk group is updated to at least version 140, by running the vxdg upgrade command on it: # vxdg upgrade diskgroup 2 On each host that can access the disk group, define the site name: # vxdctl set site=sitename 3 Tag all the disks in the disk group with the appropriate site name: # vxdisk [-g diskgroup] settag disk site=sitename 4 R
38 Remote mirror solutions About Remote Mirror configurations
Glossary application volume An application volume is created by ISP, and then exported for use by an application such as a database or file system. It is used with applications in the same way that you would use traditional non-ISP volumes that you have created by using vxassist and other VxVM commands, or via the graphical user interface. capability A capability is a feature that is provided by a volume. For example, a volume may exhibit capabilities such as performance and reliability to various degrees.
40 Glossary snapshot A copy of the data in a volume (volume snapshot) or in a file system (file system snapshot) at a moment in time. storage attribute A storage attribute allows the properties of a LUN to be defined in an arbitrary conceptual space. You can use disk tags to create storage attributes in addition to those that are intrinsically associated with the disk hardware, and which are automatically discovered or assigned by VxVM.
Glossary volume template A volume template (or template for short) is a meaningful collection of rules that provide a capability. A template can specify one or more capabilities that a volume created using the template may have, and consists of a collection of storage selection and layout rules. For example, a template may allow you to create a volume that is able to tolerate the failure of a certain number of controllers, or that has a certain number of copies of the volume data.
42 Glossary
Index C capabilities introduced 11 D decision support implementing 30 disk groups making site-consistent 37 I Intelligent Storage Provisioning (ISP) introduced 7 ISP basic concepts 8 creating volumes 13 introduced 7 language 12 solutions 12 L logical units (LUNs) introduced 8 LUNs introduced 8 tagging 14 M mirrored volumes creating 14 O off-host online backup implementing 28 off-host processing implementing 26
44 Index introduced 25 P point-in-time copies introduced 25 R redundancy of volumes 13 Remote Mirror feature configurations 33 introduced 33 site consistency 34 site-based allocation 34 rules introduced 11 S site consistency 34 site-based allocation 34 site-consistent disk groups 37 site-consistent volumes 35 snapshots introduced 25 solutions off-host processing 25 Remote Mirror 33 tiered storage 19 using ISP 12 storage attributes tags 14 storage pools introduced 8 storage tiers introduced 19 policies f
Index U user templates introduced 12 using to create volumes 16 V volume templates introduced 11 volumes creating multiple 15 creating using ISP 13 ensuring redundancy of 13 making site consistent 35 mirroring 14 simplifying creation of 16 tagging 15 45
46 Index
