Administering Storage Pools in PowerVM

File Storage Pool

In many cases, the use of SAN LUNs via NPIV is not suitable for the rapid provisioning of client LPARs. The SAN LUNs must first be created on the external storage systems and then the zoning in the SAN fabric must be adjusted, so that the new SAN LUNs are visible to the WWPNs of the client LPAR. Using VSCSI to map the SAN LUNs to the client LPARs also requires some effort. Each SAN LUN is assigned to one or more client LPARs via VSCSI, which can lead to a large number of SAN LUNs on the virtual I/O servers.

One way to provide storage for client LPARs more quickly, is to use storage pools on the virtual I/O servers. Once a storage pool has been created, storage can be made available for client LPARs with just one command. So-called backing devices are generated in the storage pool, which can be assigned to the client LPARs via virtual SCSI. Storage for client LPAR can thus be made available by the virtual I/O servers via PowerVM. This means that, for example, a boot disk, for a new client LPAR, can be created within a few seconds and can be used immediately.

PowerVM offers two different types of storage pools: local storage pools and shared storage pools. A local storage pool, or simply storage pool, is only available on one virtual I/O server. Each virtual I/O server has its own independent storage pools. A shared storage pool, on the other hand, can be made available by several virtual I/O servers that are combined in a cluster. Access to the shared storage pool is possible from each virtual I/O server that belong to the cluster. Shared storage pools are not dealt with in this chapter.

There are two types of local storage pools: logical volume storage pools and file storage pools. With a logical volume storage pool, storage is made available for the client LPARs in the form of logical volumes, with a file storage pool in the form of files.

Figure 8.13 shows a logical volume storage pool. The storage pool is implemented in the form of a volume group and therefore draws its storage capacity from the associated physical volumes. In order to provide storage for client LPARs, logical volumes are created in the storage pool. In the figure, the logical volumes bd01, bd02 and bd03 have been created. The logical volumes are referred to as backing devices, because they ultimately serve as the storage location for the data of the client LPARs. The assignment of a backing device to a client LPAR, more precisely a vhost adapter, which is assigned one-to-one to a virtual SCSI adapter of a client LPAR, takes place using a so-called virtual target device (vtscsi0, vtscsi1 and vtscsi2 in the figure). The virtual target device is a child device of one of the vhost adapters and points to the corresponding backing device via the device attribute aix_tdev. When mapping, the virtual target device is created as a child of a vhost adapter.

Logical Volume Storage Pool
Figure 8.13: Logical Volume Storage Pool

As long as the storage pool still has free capacity, additional backing devices can be created and assigned to client LPARs at any time. The provisioning of storage for client LPAR is therefore very flexible and, above all, very fast and is completely under the control of the PowerVM administrator.

In addition to logical volume storage pools, file storage pools are also supported. Such a file storage pool is shown in figure 8.14; it is implemented as a file system. The underlying logical volume is in the logical volume storage pool mypool. The storage pool name is used as the name for the logical volume, in the figure then name filepool is used. The file system is mounted under /var/vio/storagepools/filepool, whereby the last path component is the same as the storage pool name. Files are used as backing devices, the file name being the same as the backing device name. The mapping is still implemented using virtual target devices, in the figure vtscsi3 and vtscsi4 are shown as examples. The attribute aix_tdev of the virtual target devices points in this case to the respective file in the file storage pool.

File Storage Pool
Figure 8.14: File Storage Pool

Multiple Shared Processor Pools: Entitled Pool Capacity

Distribution of processor shares to shared processor pools and LPARs in the default shared processor pool according to EPC or EC.

An important change when using shared processor pools in PowerVM concerns the distribution of unused processor shares of the LPARs. Without shared processor pools, unused processor shares are divided among all uncapped LPARs according to their weights. As soon as shared processor pools are used, the distribution takes place in two stages. Unused processor shares are first distributed to uncapped LPARs within the same shared processor pool. Only the unused processor shares that are not consumed by other LPARs in the same shared processor pool are redistributed to LPARs in other shared processor pools.

Each shared processor pool has a so-called Entitled Pool Capacity (EPC), which is the sum of the guaranteed entitlements of the assigned LPARs and the Reserved Pool Capacity (RPC). The reserved pool capacity can be configured using the reserved_pool_proc_units attribute of the shared processor pool and has the default value 0. Just as the entitlement is guaranteed for a shared processor LPAR, the assignment of the entitled pool capacity is guaranteed for a shared processor pool , regardless of how the shares are then distributed to the associated LPARs in the shared processor pool. Figure 5.15 shows reserved, entitled and maximum pool capacities for a shared processor pool.

The following condition must always be met for the pool capacities:

Reserved Pool Capacity <= Entitled Pool Capacity <= Maximum Pool Capacity

The pool capacities are always shown in the output of “ms lsprocpool“:

$ ms lsprocpool ms06
ms06     DefaultPool   0   7.90      -         -        7.90      -
ms06     SharedPool01  1   0.60      0.10      0.10     0.70      1.00

In the column EC_LPARS the guaranteed entitlements of the assigned LPARs are added up, here 0.60 for the pool SharedPool01. The column RESERVED shows the reserved pool capacity (0.10 for SharedPool01), the column ENTITLED shows the entitled pool capacity and finally the column MAX shows the maximum pool capacity. (The SharedPool01 is the shared processor pool from Figure 5.15.)

The figure above shows how the distribution of processor shares works in the presence of several shared processor pools.

Each shared processor pool receives a share of the processors (cores) according to its entitled pool capacity. Shared processor LPARs in the default shared processor pool receive processor shares according to their entitlement. The unused processor shares are distributed to all LPARs, regardless of shared processor pools, according to their weights (this is not shown in the diagram).

The processor shares assigned to each shared processor pool (according to the entitled pool capacity) are then distributed within the shared processor pool to the associated LPARs according to their entitlement. That means in particular that every LPAR in a shared processor pool continues to receive its guaranteed entitlement!

If an LPAR in a shared processor pool does not consume its entitlement, then these unused processor shares are first distributed within the shared processor pool to other LPARs that need additional processor shares. The distribution then takes place as before, taking into account the weights of the LPARs. Unused processor shares are thus, so to speak, “recycled” within a shared processor pool. If not all unused processor shares in the shared processor pool are used up in this way, then these are redistributed to all LPARs (LPARs with a need for additional processor shares) via the hypervisor, regardless of the associated shared processor pool.

This two-stage distribution of processor shares can be observed very well in a small experiment. We have increased the guaranteed entitlement to 0.8 for the 3 LPARs (lpar1, lpar2 and lpar3):

$ lpar addprocunits lpar1 0.4
$ lpar addprocunits lpar2 0.4
$ lpar addprocunits lpar3 0.4

The assignment to the shared processor pools remains: lpar1 and lpar2 are assigned to the shared processor pool benchmark and lpar3 remains assigned to the default pool:

$ lpar -m ms11 lsproc
           PROC         PROCS           PROC_UNITS                        UNCAP   PROC    
lpar1      shared  1    4        8    0.1  0.8      2.0  uncap            100     benchmark
lpar2      shared  1    4        8    0.1  0.8      2.0  uncap            100     benchmark
lpar3      shared  1    4        8    0.1  0.8      2.0  uncap            100     DefaultPool
ms11-vio1  ded     1    7        8    -    -        -    keep_idle_procs  -       -
ms11-vio2  ded     1    6        8    -    -        -    keep_idle_procs  -       -

In the shared processor pool benchmark, the resulting entitled pool capacity is 2 * 0.8 + 0.0 = 1.6 (the reserved pool capacity is 0.0). The entitled pool capacity of the default Shared Processor Pool with only one LPAR is 0.8.

$ ms lsprocpool ms11
ms11     DefaultPool  0   0.80      -         -        0.80      -
ms11     testpool     1   0.00      0.00      0.00     0.00      2.00
ms11     benchmark    2   1.60      0.00      0.00     1.60      2.00

We start the benchmark again, this time on lpar1 (shared processor pool benchmark) and lpar3 (shared processor pool DefaultPool) in parallel. No load is placed on lpar2 (Shared Processor Pool benchmark), the LPAR is at a load of approx. 0.00 – 0.01 during the benchmark. This means that the guaranteed entitled pool capacity of 1.6 is available exclusively for lpar1! The guaranteed entitlement of lpar2 in the default pool is only 0.8. Of the 3 physical processors (cores) in the physical shared processor pool, only an entitlement of 3.0 – 1.6 – 0.8 = 0.6 remains, which can be distributed to LPARs with additional processor components. Since lpar1 and lpar3 both have the same weights (uncap_weight=100), they each receive an additional 0.3 processing units. That makes for lpar1: 1.6 + 0.3 = 1.9. And for lpar3: 0.8 + 0.3 = 1.1. This can be seen very nicely in the graphics for the processor utilization (figure 5.17). A short time after the start of the benchmark, on lpar1 around 1.9 physical processors (cores) are used and on lpar3 around 1.1. Due to the larger processor shares, the benchmark on lpar1 is finished faster, which means that the processor utilization goes down there. However, lpar3 has then more processor shares available and lpar3 then takes almost all of the 3 available processors at the end.

Without additional shared processor pools, all uncapped LPARs benefit from unused processor shares that an LPAR does not use. Since potentially all LPARs get shares of these unused processor shares, the proportion for an individual LPAR is not so large. If additional shared processor pools are used, uncapped LPARs in the same shared processor pool benefit primarily from unused processor shares of an LPAR. These are fewer LPARs and therefore the proportion of additional processor capacity per LPAR is higher.

5.5. Multiple Shared Processor Pools

5.5.1. Physical Shared Processor Pool

5.5.2. Multiple Shared Processor Pools

5.5.3. Configuring a Shared Processor Pool (Maximum Pool Capacity)

5.5.4. Assigning a Shared Processor Pools

5.5.5. Entitled Pool Capacity (EPC)

5.5.6. Reserved Pool Capacity (RPC)

5.5.7. Deactivating a Shared Processor Pool

Adding Logical SR-IOV Ports

SR-IOV Ethernet port with internal switch and 3 logical ports.

In order that an LPAR can use a virtual function of an SR-IOV adapter in PowerVM, a so-called logical port must be created for the LPAR. Which logical ports already exist can be displayed with the command “ms lssriov” and the option “-l” (logical port):

$ ms lssriov -l ms03

Since the SR-IOV adapters have just been configured to shared mode, there are of course no logical ports yet. To add a logical SR-IOV port to an LPAR, the command “lpar addsriov” (add SR-IOV logical port) is used. In addition to the LPAR, the adapter ID and the port ID of the physical port must be specified. Alternatively, a unique suffix of the physical location code of the physical port can also be specified:

$ lpar addsriov aix22 P1-C11-T1

The creation can take a few seconds. A quick check shows that a logical port has actually been created:

$ ms lssriov -l ms03
U78AA.001.VYRGU0Q-P1-C11-T1-S1  1        0      27004001  aix22  2.0       a1b586737e00   -

Similar to a managed system for virtual Ethernet, an internal switch is implemented on the SR-IOV adapters for each physical Ethernet port, see figure above. One of the virtual functions is assigned to each logical port. The associated LPARs access the logical ports directly via the PCI Express bus (PCIe switch).

An LPAR can easily have several logical SR-IOV ports. With the command “lpar lssriov” (list SR-IOV logical ports) all logical ports of an LPAR can be displayed:

$ lpar lssriov aix22
27004001  Yes  1        0      0          2.0       100.0         0     all    a1b586737e00   -

There are a number of attributes that can be specified for a logical port when it is created. Among other things, the following properties can be configured:

    • capacity – the guaranteed capacity for the logical port.
    • port_vlan_id – the VLAN ID for untagged packets or 0 to switch off VLAN tagging.
    • promisc_mode – switch promiscuous mode on or off.

The complete list of attributes and their possible values can be found in the online help (“lpar help addsriov“).

As an example we add another logical port with port VLAN-ID 55 and a capacity of 20% to the LPAR aix22:

$ lpar addsriov aix22 P1-C4-T2 port_vlan_id=55 capacity=20

The generated logical port thus has a guaranteed share of 20% of the bandwidth of the physical port P1-C4-T2! The LPAR now has 2 logical SR-IOV ports:

$ lpar lssriov aix22
27004001  Yes  1        0      0          2.0       100.0         0     all    a1b586737e00   -
2700c003  Yes  3        2      1          20.0      100.0         55    all    a1b586737e01   -

After the logical ports have been added to the LPAR using the PowerVM Hypervisor, they appear in the Defined state. The logical ports appear under AIX as ent devices, like all other Ethernet adapters!

aix22 # lsdev -l ent\*
ent0 Available       Virtual I/O Ethernet Adapter (l-lan)
ent1 Defined   00-00 PCIe2 10GbE SFP+ SR 4-port Converged Network Adapter VF (df1028e214100f04)
ent2 Defined   01-00 PCIe2 100/1000 Base-TX 4-port Converged Network Adapter VF (df1028e214103c04)
aix22 #

After the config manager cfgmgr has run, the new ent devices are in the Available state and can be used in exactly the same way as all other Ethernet adapters.

7.6. SR-IOV

7.6.1. Activating Shared Modes

7.6.2. Configuration of Physical SR-IOV Ports

7.6.3. Adding Logical SR-IOV Ports

7.6.4. Changing a Logical SR-IOV Port

7.6.5. Removing Logical SR-IOV Ports

7.6.6. Setting an SR-IOV Adapter from Shared back to Dedicated

Adding a Virtual Ethernet Adapter

Delivery of tagged packets, here for the VLAN 200.

If in a PowerVM environment a virtual Ethernet adapter is to be added to an active LPAR using the LPAR-Tool, the LPAR must have an active RMC connection to an HMC. This requires an active Ethernet adapter (physical or virtual). A free virtual slot is required for the virtual Ethernet adapter.

$ lpar lsvslot aix22
0     Yes  serial/server  1      remote: (any)/any connect_status=unavailable hmc=1
1     Yes  serial/server  1      remote: (any)/any connect_status=unavailable hmc=1
5     No   eth            1      PVID=100 VLANS= ETHERNET0 1DC8DB485D1E
10    No   fc/client      1      remote: ms03-vio1(1)/5 c05076030aba0002,c05076030aba0003
20    No   fc/client      1      remote: ms03-vio2(2)/4 c05076030aba0000,c05076030aba0001

The virtual slot 6 is not yet used by the LPAR aix22. A virtual Ethernet adapter can be added with the command “lpar addeth“. At least the desired virtual slot number for the adapter and the desired port VLAN ID must be specified:

$ lpar addeth aix22 6 900

In the example, a virtual Ethernet adapter for aix22 with port VLAN ID 900 was created in slot 6. If the slot number doesn’t matter, the keyword auto can be specified instead of a number; the LPAR tool then automatically assigns a free slot number. The virtual adapter is available immediately, but must first be made known to the operating system. How this happens exactly depends on the operating system used. In the case of AIX there is the cfgmgr command for this purpose.

After the virtual Ethernet adapter has been added, but before a run of cfgmgr is started, only the virtual Ethernet adapter ent0 is known to the AIX operating system of the LPAR aix22:

aix22 # lscfg -l ent*
  ent0             U9009.22A.8991971-V30-C5-T1  Virtual I/O Ethernet Adapter (l-lan)
aix22 #

After a run of cfgmgr the newly added virtual Ethernet adapter appears as ent1:

aix22 # cfgmgr
aix22 # lscfg -l ent*
  ent0             U9009.22A.8991971-V30-C5-T1  Virtual I/O Ethernet Adapter (l-lan)
  ent1             U9009.22A.8991971-V30-C6-T1  Virtual I/O Ethernet Adapter (l-lan)
aix22 #

Note: On AIX, the device name for an Ethernet adapter cannot be used to identify the type. Regardless of whether an Ethernet adapter is physical or virtual or a virtual function of an SR-IOV adapter, the device name ent with an ascending instance number is always used.

If an IEEE 802.1q compatible virtual Ethernet adapter with additional VLAN IDs is to be created, the option “-i” (IEEE 802.1q compatible adapter) must be used. Alternatively, the ieee_virtual_eth=1 attribute can also be specified. The additional VLAN IDs are specified as a comma-separated list:

$ lpar addeth -i aix22 7 900 100,200,300

The port VLAN ID is 900, and the additional VLAN IDs are 100, 200 and 300.
If an LPAR has no active RMC connection or is not active, then a virtual Ethernet adapter can only be added to one of the profiles of the LPAR. This is always the case, for example, if the LPAR has just been created and has not yet been installed.

In this case, only the option “-p” with a profile name has to be used for the commands shown. Which profiles an LPAR has, can easily be found out using “lpar lsprof” (list profiles):

$ lpar lsprof aix22
standard                  ded       7168  ded        2      default
last*valid*configuration  ded       7168  ded        2      default

(The last active configuration is stored in the profile with the name last*valid*configuration.)

The virtual adapters defined in the profile standard can then be displayed by specifying the profile name with “lpar lsvslot“:

$ lpar -p standard lsvslot aix22
0     Yes  serial/server  remote: (any)/any connect_status= hmc=1
1     Yes  serial/server  remote: (any)/any connect_status= hmc=1
5     No   eth            PVID=100 VLANS= ETHERNET0 
6     No   eth            PVID=900 VLANS= ETHERNET0 
7     No   eth            IEEE PVID=900 VLANS=100,200,300 ETHERNET0 
10    No   fc/client      remote: ms03-vio1(1)/5 c05076030aba0002,c05076030aba0003
20    No   fc/client      remote: ms03-vio2(2)/4 c05076030aba0000,c05076030aba0001

When adding the adapter, only the corresponding profile name has to be given, otherwise the command looks exactly as shown above:

$ lpar -p standard addeth -i aix22 8 950 150,250

In order to make the new adapter available in slot 8, the LPAR must be activated again by default, specifying the profile name.

7.3. Virtual Ethernet

7.3.1. VLANs and VLAN Tagging

7.3.2. Adding a Virtual Ethernet Adapter

7.3.3. Virtuelle Ethernet Switches

7.3.4. Virtual Ethernet Bridge Mode (VEB)

7.3.5. Virtual Ethernet Port Aggregator Mode (VEPA)

7.3.6. Virtual Networks

7.3.7. Adding and Removing VLANs to/from an Adapter

7.3.8. Changing Attributes of a Virtual Ethernet Adapter

7.3.9. Removing a Virtual Ethernet Adapter