Adding a Cache, Meta, or Log Device to an Existing Storage Pool (CLI)

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Use the following task to add a read cache device or log device to an existing storage pool.

Before You Begin

For recommendations on how many drives to select per pool, as well as other considerations and guidelines, see Storage Pool Concepts.
You must select the same data profile currently used in the existing pool. To understand the different data profiles, see Data Profiles for Storage Pools.
Do not perform a pool configuration operation while a disk firmware upgrade is occurring. To check if an upgrade is in progress, navigate to maintenance system updates.
A meta device must be a 3.2 TB (minimum) SSD to support the enhanced data deduplication feature available in software version OS8.7.0 or later.

Install the new log, read cache, or meta device into the first available and appropriate slot. To determine the appropriate slot, see Disk Shelf Configurations in Oracle ZFS Storage Appliance Customer Service Manual.
Go to configuration storage.
If you have multiple pools, a default pool is selected and displayed. If this is not the pool to which you want to add a device, enter set pool= and specify another online pool.
Note - If you have a single pool, the pool name is not displayed, but it is selected.
```
hostname:configuration storage (pool0)> set pool=pool1
                            pool = pool1
```
A message reminds you to verify that storage is correctly attached and functioning.

Enter add:

hostname:configuration storage (pool1)> add

Enter show to display device information for the pool.

hostname:configuration storage (pool1) verify> show
ID STATUS  ALLOCATION  DATA   LOG      CACHE   META     RPM
0      ok     custom      0   0          0/4    0/4    1.86T
1      ok     custom      0   0/2  34G     0      0    15000
2      ok     custom      0   0/2  34G   0/2      0    15000

Enter set and use tab completion to see if cache, meta, and log devices are available.
```
hostname:configuration storage (pool1) verify> set
0-cache  1-data   2-cache  2-meta  2-log
```
Enter set and the disk shelf or controller ID, and the number of log, cache, or meta devices to use.
ID "0" is the controller, and the remaining IDs are the disk shelves. In the following example, 2-log=1 allocates one log device from the second disk shelf.
```
hostname:configuration storage (pool1) verify> set 2-log=1
                            2-log = 1
```
Note - A value of "1-log=2" would allocate two log devices from the first disk shelf.

This example allocates one cache device from the second disk shelf.
```
hostname:configuration storage (pool1) verify> set 2-cache=1
                            2-cache = 1
```
This example allocates one meta device from the second disk shelf:
```
hostname:configuration storage (pool1) verify> set 2-meta=1
                            2-meta = 1
```

Enter done.

hostname:configuration storage (pool1) verify> done

Enter show to display the profile.

hostname:configuration storage (pool1) config> show
PROFILE                   CAPCTY   NSPF   DESCRIPTION
log_profile = log_stripe     17G     no   Striped log

Note - If you allocated cache devices to the pool, the profile is always striped.

If you allocated log devices to the pool, enter set log_profile= and set the log profile to either log_mirror or log_stripe. Use log_mirror if the pool now contains an even number of log devices.

Caution - A double failure can cause loss of data from a log in a striped configuration. It is highly recommended to configure a mirrored log profile for added redundancy. For more information, see Data Profiles for Storage Pools.

hostname:configuration storage (pool1)> set log_profile=log_mirror

If you allocated meta devices to the pool, enter set meta_profile= and set the meta profile to either meta_mirror or meta_stripe.
```
hostname:configuration storage (pool1)> set meta_profile=meta_mirror
```

Enter done to complete the task.

hostname:configuration storage (pool1)> done

Oracle^® ZFS Storage Appliance Administration Guide, Release OS8.7.x

Adding a Cache, Meta, or Log Device to an Existing Storage Pool (CLI)

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