Chapter 10. IBM SAN Volume Controller, IBM Storwize V7000, and IBM Storwize V7000 Unified Storage 151
10.5.2 User data pool
Regarding user data pools:
Use RAID for data protection and performance. The RAID type depends on the disk
category, but is usually RAID 5 or RAID 6.
Do not share the user data pool with the metadata pool.
Create a single pool for user data that contains all the user data MDisks.
Specify an extent size default of 256 MB for each user data volume created.
For each user data MDisk, create a single user data (UD) volume to accommodate the full
size of each user data MDisk, by using the
sequential virtualization type.
The size of user data volumes must be consistent.
Create at least seven user data volumes for optimal performance. Optimal configurations
of SAN Volume Controller and Storwize V7000 require at least four 4 arrays to ensure
maximal core usage. You should have more than 24 user data volumes.
10.5.3 Expanding the repository
When expanding the repository, use the same spindle type and quantity of RAID groups for
metadata or user data. For example, if the original two metadata LUNs were built on RAID
4+4 groups, then the added metadata RAID groups must be at least 4+4 to maintain the
same level of performance. Using storage from 2+2 or 4+1 RAID groups, for example, for the
expansion might degrade performance because of an Input/Output Operations Per Second
10.6 Configuration steps
Figure 10-5 shows the steps to configure the ProtecTIER repository in a storage
Figure 10-5 Configuration steps
Important: The total number of volumes for both the ProtecTIER repository for metadata
(MD) and user data (UD) should not exceed 170. Each volume size should not exceed
6 TB, to comply with the 1 PB ProtecTIER repository size limit.
With ProtecTIER 3.2, the 8 TB restriction is removed. When the individual disk size is large
(for example, 2 or 3 TB), use RAID 6 with 6+2 disk members.
152 IBM ProtecTIER Implementation and Best Practices Guide
The steps are:
1. Create user data and metadata empty storage pools.
2. Create the MDisk arrays or discover unmanaged MDisks.
3. Create a host connection for the ProtecTIER nodes.
4. Create volumes (VDisks) with a sequential virtualization type the command-line
5. Map volumes to the host.
6. Create file systems using the File Systems Management under the ptconfig menu and
build the ProtecTIER repository using the ProtecTIER Manager.
10.6.1 Creating empty user data and metadata storage pools
You should create only two storage pools (also known as managed disk groups), where one
is used for metadata and the other is used for user data. When creating more pools, the
storage system cache is segmented among all pools. By having only two pools, you optimize
the storage subsystem cache allocation.
To create these items, complete the following steps:
1. Hover your cursor over the Pools icon, and the system displays the Pools menu
(Figure 10-6). Click MDisks by Pools.
Figure 10-6 Pool menu
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2. For each pool, click New Pool to create an empty pool. Insert a name for the pool, such as
MD_pool or UD_pool. Keep the extent size settings of 256 MB to have 1 PB of
virtualization within the storage. You can also change the warning threshold to 100% to
not receive alerts about pool utilization, as it is fully allocated by the ProtecTIER LUNs
Figure 10-7 Creating pools
3. Click Next. If you already created your MDisk arrays or use MDisks from external storage,
select the MDisks to be included in the pool. Otherwise, click Finish to create the empty
4. Repeat this procedure for the next pool.
The steps can also be done by using the CLI, as shown in Example 10-2.
Example 10-2 Creating a pool using the CLI
# svctask mkmdiskgrp -ext 256 -warning 100% -name UD_pool
10.6.2 Creating the MDisk arrays or discovering unmanaged MDisks
When using the Storwize V7000 and Storwize V7000 Unified servers, you can use internal or
external disks to create MDisks. The SAN Volume Controller allows only MDisks coming from
an external virtualized storage.