Configure ASC SAN Resources

SAN Resources

SAN Resources are logically mapped devices on the ASC Server. They are comprised of physical storage devices, known as Physical Resources in ASC. Physical resources are the actual SCSI and/or Fibre Channel devices attached to the server. These devices can be hard disks, tape drives, device libraries, JBODs and RAID cabinets.

Clients do not have access to physical resources; they have access only to SAN Resources. This means that physical resources must be defined as SAN (or NAS) Resources first, and then assigned to the clients so they can access them

When a SAN Resource is assigned to a client, a virtual adapter is defined for that client. The SAN Resource is assigned a virtual SCSI ID on the virtual adapter. This mimics the configuration of actual SCSI storage devices and adapters, allowing the operating system and applications to treat them like any other SCSI device.

There are three types of SAN Resources: virtual devices, direct devices, and service enabled devices.

Virtual devices

ASC has the ability to aggregate multiple physical storage devices (such as JBODs and RAIDs) of various interface protocols (such as SCSI or Fibre Channel) into logical storage pools. From these storage pools, virtual devices can be created and provisioned to application servers and end users. This is called storage virtualization.

Virtual devices are defined as sets of storage blocks from one or more physical hard disk drives. This allows the creation of virtual devices that can be a portion of a larger physical disk drive, or an aggregation of multiple physical disk drives.

Virtual devices offer the added capability of disk expansion. Additional storage blocks can be appended to the end of existing virtual devices without erasing the data on the disk.

Virtual devices can only be assembled from hard disk storage. It does not work for CD-ROM, tape, libraries, or removable media.

When a virtual device is allocated to an application server, the server thinks that an actual SCSI storage device has been physically plugged into it.

Virtual devices are assigned to virtual adapter 0 (zero) when mapped to a client. If there are more than 15 virtual devices, a new adapter will be defined.

Note: We do not recommend storing system files, page files, swap files, etc. on ASC virtual devices.

Direct devices

Direct devices are directly mapped SCSI devices. Direct devices can be created from hard disks, tape drives, device libraries, JBODs, and RAID cabinets.

Because they are not virtualized, direct devices cannot take advantage of ASC's advanced storage management options, such as mirroring, replication, or snapshot copy.

Direct devices, such as tape drives, device libraries, JBODs, and RAID cabinets, can be used to back up data on your storage network.

A characteristic of some application software, such as backup tools and devices, require that they address the SCSI ID directly. This is true for library devices and the drives within the library; the software uses the SCSI IDs to address the library and drives. For this reason, direct devices use fixed SCSI IDs that cannot be changed.

Service enabled devices

Service enabled devices are hard drives with existing data that can be accessed by ASC to make use of all key ASC storage services (mirroring, snapshot, etc.), without any migration/copying, without any modification of data, and with minimal downtime. Service enabled devices are used to migrate existing drives into the SAN.

Because service enabled devices are preserved intact, and existing data is not moved, the devices are not virtualized and cannot be expanded. Service enabled devices are all maintained in a one-to-one mapping relationship (one physical disk equals one logical device). Unlike virtual devices, they cannot be combined or split into multiple logical devices.

Prepare devices to become SAN Resources

You can use one of ASC's disk preparation options to change the category of a device. This is important to do if you want to create a logical resource using a device that is currently unassigned.

• The ASC Server detects new devices when you connect to it (or when you execute the Rescan command). When they are detected you will see a dialog box notifying you of the new devices. At this point you can highlight a device and press the Prepare Disk button to prepare it.
• At any time, you can prepare a single unassigned device by doing the following: Highlight the device, right-click, select Properties and select the device category. (You can find all unassigned devices under the Physical Resources/Adapters node of the tree view.)
• For multiple unassigned devices, highlight Physical Resources, right-click and select Prepare Disks. This launches a wizard that allows you to virtualize, unassign, or import multiple devices at the same time.

Create a virtual device SAN Resource

1. Right-click on SAN Resources and select New.
2. Select Virtual Device.
3. Select how you want to create this virtual device.

   Custom lets you select which physical device(s) to use and lets you designate how much space to allocate from each.

   Express lets you designate how much space to allocate and then automatically creates a virtual device using all available devices.

   Batch lets you create multiple SAN Resources at one time. These SAN Resources will all be the same size.

4. (Express and Custom only) Enter a name for the new SAN Resource.
5. Confirm that all information is correct and then click Finish to create the virtual device SAN Resource.
6. (Express and Custom only) Indicate if you would like to assign the new SAN Resource to a client.

   If you select Yes, the Assign a SAN Resource Wizard will be launched.

Create a direct device or service enabled device SAN Resource

1. Right-click on SAN Resources and select New.
2. Select Direct Device or Service Enabled Device.
3. Select the device that you want to make into a direct/service enabled device.

   A list of the physical resources that have been reserved for this purpose are displayed. For direct devices, both hard disk and non-hard disk devices are shown.

4. (Service enabled devices only) Select the physical device for the service enabled device's virtual header.

   Even though service enabled devices are used as is, a virtual header is created on another physical device to allow ASC's storage services to be supported.

5. Enter a name for the new SAN Resource.
6. Confirm that all of the information is correct and then click Finish to create the SAN Resource.
7. Indicate if you would like to assign the new SAN Resource to a client.

   If you select Yes, the Assign a SAN Resource Wizard will be launched.

Assign a SAN Resource to one or more clients

Notes:

- (For Windows NT 4.0 Fibre Channel clients running DynaPath) If you are assigning SAN Resources, you must reboot the Windows NT machine before making the assignments.

- (For AIX Fibre Channel clients running DynaPath) If you are re-assigning SAN Resources to the same LUN, you must reboot the AIX client after unassigning a SAN Resource.

1. Right-click on a SAN Resources object and select Assign.

   The wizard can also be launched from the Create SAN Resource wizard.

2. If this server has multiple protocols enabled, select the type of client to which you will be assigning this SAN Resource.
3. Select the SAN Resource to be assigned.

   SAN/IP clients

   If the SAN/IP client that you want to assign to the SAN Resource does not appear on the list, click the Add button.

   You can add any application server, even if it is currently offline or has not yet had ASC Client software installed. However, in order for the server to use the ASC storage resources, you must install the ASC SAN Client software on the server and "authorize" the client's access to the ASC SAN resources.

   Note: You must enter the client's name, not an IP address.

   Fibre Channel clients

   Read/Write - Only one client can access this SAN Resource at a time. All others (including Read Only) will be denied access. This is the default.

   Read/Write Non-Exclusive - Two clients can connect at the same time with both read and write access. You should be careful with this option because if you have multiple clients writing to a device at the same time, you have the potential to corrupt data. This option should only be used by clustered servers, because the cluster itself prevents multiple clients from writing at the same time.

   Read Only - This client will have read only access to the SAN Resource. This option is useful for a read-only disk.

4. If this is a Fibre Channel client and you are using Data Multiple Path software (such as ASC's DynaPath), enter the World Wide Port Name (WWPN) mapping.

   This WWPN mapping is similar to Fibre Channel zoning and allows you to provide multiple paths to the ASC Server to limit a potential point of network failure. You can select how the client will see the virtual device in the following ways:

   One to One - Limits visibility to a single pair of WWPNs. You will need to select the client's Fibre Channel initiator WWPN and the server's Fibre Channel target WWPN.

   One to All - You will need to select the client's Fibre Channel initiator WWPN.

   All to One - You will need to select the server's Fibre Channel target WWPN.

   All to All - Creates multiple data paths. If ports are ever added to the client or server, they will automatically be included in the WWPN mapping.

5. If this is a Fibre Channel client and you selected a One to n option, select which port to use as an initiator for this client.
6. If this is a Fibre Channel client and you selected an n to One option, select which port to use as a target for this client.
7. Confirm all of the information and then click Finish to assign the SAN Resource to the client(s).

   The SAN Resource will now appear under the SAN Client in the configuration tree view.

   Note: Depending upon the operating system of the client, you may be required to reboot the client machine in order to be able to use the new SAN Resource.

Assign a client to one or more SAN Resources

Notes:

- (For Windows NT 4.0 Fibre Channel clients running DynaPath) If you are assigning SAN Resources, you must reboot the Windows NT machine before making the assignments.

- (For AIX Fibre Channel clients running DynaPath) If you are re-assigning SAN Resources to the same LUN, you must reboot the AIX client after unassigning a SAN Resource.

1. Right-click on a SAN Client and select Assign.
2. Select the SAN Resource to be assigned.

   Read/Write - Only one client can access this SAN Resource at a time. All others (including Read Only) will be denied access. This is the default.

   Read/Write Non-Exclusive - Two clients can connect at the same time with both read and write access. You should be careful with this option because if you have multiple clients writing to a device at the same time, you have the potential to corrupt data. This option should only be used by clustered servers, because the cluster itself prevents multiple clients from writing at the same time.

   Read Only - This client will have read only access to the SAN Resource. This option is useful for a read-only disk.

3. If this is a Fibre Channel client and you are using Data Multiple Path software (such as ASC's DynaPath), enter the World Wide Port Name (WWPN) mapping.

   This WWPN mapping is similar to Fibre Channel zoning and allows you to provide multiple paths to the ASC Server to limit a potential point of network failure. You can select how the client will see the virtual device in the following ways:

   One to One - Limits visibility to a single pair of WWPNs. You will need to select the client's Fibre Channel initiator WWPN and the server's Fibre Channel target WWPN.

   One to All - You will need to select the client's Fibre Channel initiator WWPN.

   All to One - You will need to select the server's Fibre Channel target WWPN.

   All to All - Creates multiple data paths. If ports are ever added to the client or server, they will automatically be included in the WWPN mapping.

4. If this is a Fibre Channel client and you selected a One to n option, select which port to use as an initiator for this client.
5. If this is a Fibre Channel client and you selected a n to One option, select which port to use as a target for this client.
6. Confirm all information and click Finish to assign this client.

   Note: Depending upon the operating system of the client, you may be required to reboot the client machine in order to be able to use the new SAN Resource.

Expand a virtual device

Since virtual devices do not represent actual physical resources, they can be expanded as more storage is needed. The virtual device can be increased in size by adding more blocks of storage from any unallocated space from the same server.

Note that you will still need to repartition the virtual devices and adjust/create/resize any file-systems on the partition after the virtual device is expanded. Since partition and file-system formats are specific to the operating system that the client is running, the administrator must perform these tasks directly from the client. You can use tools like Partition Magic, Windows 2000 Dynamic Disk, or Veritas Volume Manager to add more drives to expand existing volume on-the-fly in real time (without application down time).

Notes:

• We do not recommend expanding a virtual device (SAN or NAS) while clients are accessing the drives.
• At the end of this section is important information about Windows 2000 dynamic disks, Solaris clients, AIX clients, and Fibre Channel clients.
• Right-click on a virtual device (SAN or NAS) and select Expand.
• Select how you want to expand the virtual device.

  Custom lets you select which physical device(s) to use and lets you designate how much space to allocate from each.

  Express lets you designate how much space to allocate and then automatically creates a virtual device using all available devices.

  The Total Available Size is the maximum space available on all available devices. If this drive is mirrored, this number will be half the full amount because the mirrored drive will need an equal amount of space.

• Confirm that all information is correct and then click Finish to expand the virtual device.

Windows 2000 Dynamic disks

Expansion of dynamic disks using the Expand SAN Resource Wizard is not supported for clients using either SAN/IP or Fibre Channel. Due to the nature of dynamic disks, it is not safe to alter the size of the virtual device. However, dynamic disks do provide an alternative method to extend the dynamic volume.

To extend a dynamic volume using SAN Resources, use the following steps:

1. Create a new SAN Resource and assign it to the ASC Client. This will become an additional disk which will be used to extend the dynamic volume.
2. Use Disk Manager to write the disk signature and upgrade the disk to "Dynamic".
3. Use Disk Manager to extend the dynamic volume.

   The new SAN Resource should be available in the list box of the Dynamic Disk expansion dialog.

Solaris clients

The following procedure is valid for clients using Fibre Channel and SAN/IP:

1. Use expand.sh to get the new capacity of the disk.

   This will automatically label the disk.

2. Use the format utility to add a new partition or, if your file system supports expansion, use your file system's utility to expand the file system.

Windows clients (Fibre Channel)

You must restart your Windows NT client after expanding a virtual device in order for the expanded area to become available. For Windows 2000 clients, you should rescan the physical devices from the Computer Manager to see the expanded area.

Linux clients (Fibre Channel)

1. Use rmmod qla2x00 to remove the module.
2. Use insmod qla2x00 to install the module back again.
3. Use fdisk/dev/sda to create a second partition.

   The a in sda refers to the first disk. Use b, c, etc. for subsequent disks.

AIX clients

Expanding an ASC virtual disk will not change the size of the existing AIX volume group. To expand the volume group, a new disk has to be assigned and the extendvg command should be used to enlarge the size of the volume group.

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