2    Planning LSM Volumes and Disk Groups

Planning your LSM configuration includes deciding:

• How many disk groups you need, and which disks you will configure in a disk group

• How many volumes you want, and the type of data plex the volumes will use

This chapter provides information and worksheets to assist you in planning LSM disk groups and volumes. You might want to make copies of the blank worksheets for future use.

2.1    Planning LSM Volumes

Planning LSM volumes includes deciding what attributes you want the LSM volumes to have. An LSM volume has two types of attributes:

• Attributes for which you must provide a value, as described in Table 2-1.

• Attributes that are assigned a default value, which you can change, as described in Table 2-2.

Table 2-1:  LSM Volume Attributes with No Default Values

Table 2-2:  LSM Volume Attributes with Default Values

Table 2-3:  Choosing a Plex Type

The following sections provide worksheets to assist you in planning LSM volumes depending on the type of plex you want to use. Using the information in these worksheets will help you when you create volumes as described in Chapter 4.

2.1.1    Planning an LSM Volume That Uses a Concatenated Plex

Use the following worksheet to plan an LSM volume that uses a concatenated plex.

Figure 2-1:  Worksheet for Planning a Volume with Concatenated Plexes

2.1.2    Planning an LSM Volume That Uses a Striped Plex

Use the following worksheet to plan an LSM volume that uses a striped plex.

Figure 2-2:  Worksheet for Planning a Volume with Striped Plexes

2.1.3    Planning an LSM Volume That Uses a RAID 5 Plex

Use the following worksheet to plan an LSM volume that uses a RAID 5 plex.

Figure 2-3:  Worksheet for Planning a Volume with a RAID 5 Plex

2.2    Planning Disk Groups

At a minimum, you must plan the rootdg disk group, which is created when you install LSM. Planning a disk group requires that you identify:

• How much space a disk group requires by identifying the size of volumes that you will create in the disk group, as identified in Section 2.1.

• Unused storage devices to meet the space requirement of the disk group, as identified in Section 2.3.

When you plan a disk group, consider the following:

• You must identify at least one unused storage device for the rootdg disk group when you install LSM.

• A disk group should have more than one storage device to ensure that there are multiple copies of the disk group's configuration database.

• A disk group should have storage devices on different buses because LSM can simultaneously read and write data for volumes that use mirrored or striped plexes or a RAID 5 plex.

Use the worksheets in Figure 2-4 and Figure 2-5 to plan disk groups. You can make copies and fill in the information there, rather than in the guide. This lets you keep the disk group information with each system running LSM, like a quick reference guide.

In the worksheets, enter the following:

• Under Disk Group Information, include any information that will help you keep track of the purpose of that disk group. For example, you might create a disk group called finance whose purpose is to contain one or more volumes that will be used by a financial application. You might create another disk group called oracle, which will contain a volume used by an Oracle database.

• Under Volume, Plex and Spare Disk Information, include the names of all volumes in that disk group, their plex type, which disks belong to which plex, and identify any spare disks that will be used to replace failed disks, if you enabled the hot-spare option to the volwatch daemon. Figure 2-6 is an example of a completed worksheet.

Figure 2-4:  Worksheet for Planning rootdg Disk Group

Figure 2-5:  Worksheet for Planning Additional Disk Groups

Figure 2-6 shows a combined example of what your disk group planning worksheets might look like when complete.

Figure 2-6:  Worksheet for Planning Disk Groups (Completed Example)

2.3    Identifying Unused Storage Devices

Unused storage devices are unused disks, partitions, and RAID disks that LSM can initialize to become LSM disks for exclusive use in the rootdg disk group or in the other disk groups that you create.

You can also identify unused LSM disks for use in a disk group. An unused LSM disk is a storage device that you initialized for use by LSM but did not assign to a disk group.

The following sections describe how to identify unused disks, partitions, and LSM disks. See your RAID documentation for information on identifying unused RAID disks.

To identify unused storage devices, you can use:

• The Disk Configuration Graphical User Interface (GUI)

• The command-line interface of operating system utilities

• The voldisk list command on a system where LSM is running

2.3.1    Using the Disk Configuration GUI to Identify Unused Disks

To identify unused disks using the Disk Configuration GUI, start the Disk Configuration interface using either of the following methods:

• From the system prompt, enter:

  # /usr/sbin/diskconfig
  

• From the SysMan Applications pop-up menu on the CDE Front Panel:

  1. Choose Configuration

  2. Double click the Disk icon in the SysMan Configuration folder

  A window titled Disk Configuration on hostname is displayed. This is the main window for the Disk Configuration GUI, and lists the following information for each disk:

  • The disk name, such as dsk10

  • The device model, such as RZ1CB-CA

  • The bus number for the device

  For more information about a disk, double click on the list item (or click the Configure... button when a disk is highlighted). The Disk Configuration: Configure Partitions: window is displayed. This window contains:

  • A graphical representation of the disk partitions in a horizontal bar-chart format and disk information such as the disk name, the total size of the disk, and usage information.

  • A Partition Table button that you can click to display a bar chart of the current partitions in use, their sizes, and the file system in use.

  • A Disk Attributes button that you can click to display values for disk attributes.

For more information about the Disk Configuration GUI, see the online help.

2.3.2    Using Operating System Commands to Identify Unused Disks

You can use the operating system's hwmgr and disklabel commands to identify unused disks by following these steps:

1. Use the following command to display disk and bus information:

   # hwmgr -view dev
   

   Information similar to the following is displayed:

     HWID:             DSF Name  Mfg      Model       Location
    
   ----------------------------------------------------------------------
        3:            /dev/kevm
       22:      /dev/disk/dsk0c  DEC      RZ26        bus-0-targ-3-lun-0
       23:    /dev/disk/cdrom0c  DEC      RRD42       bus-0-targ-4-lun-0
       24:      /dev/disk/dsk1c  DEC      RZ26L       bus-1-targ-2-lun-0
       25:     /dev/disk/dsk14c  DEC      RZ26L       bus-1-targ-4-lun-0
       29:     /dev/ntape/tape0  DEC      TLZ06       bus-1-targ-6-lun-0
       35:      /dev/disk/dsk8c  COMPAQ   RZ1CF-CF    bus-2-targ-12-lun-0
   

2. To verify if a disk or partition is unused, choose a disk from the previous output and enter the disklabel command with the name of the disk; for example:

   # disklabel dsk14
   

   Disk partition information similar to the following is displayed:

   # /dev/rdisk/dsk14c:
   .
   .
   .
   8 partitions:
   #          size     offset    fstype   [fsize bsize   cpg]  # NOTE: values not exact
     a:     131072          0    unused        0     0         # (Cyl.    0 - 95*)
     b:     262144     131072    unused        0     0         # (Cyl.   95*- 285*)
     c:    4110480          0    unused        0     0         # (Cyl.    0 - 2987*)
     d:          0          0    unused        0     0         # (Cyl.    0 - -1)
     e:          0          0    unused        0     0         # (Cyl.    0 - -1)
     f:          0          0    unused        0     0         # (Cyl.    0 - -1)
     g:    1858632     393216    unused        0     0         # (Cyl.  285*- 1636*)
     h:    1858632    2251848    unused        0     0         # (Cyl. 1636*- 2987*)
    
   

   See the disklabel(8) reference page for more information on the disklabel command.

2.3.3    Using the voldisk Command to Identify Unused Disks

When LSM starts, it obtains a list of disk device addresses from the operating system software and checks the disk labels to determine which devices are initialized for LSM use and which are not.

You can use the voldisk command to display a list of all known disks and to display detail information about a particular disk:

• To view a list of disks, enter:

  # voldisk list
  

  Information similar to the following is displayed.

  DEVICE       TYPE      DISK         GROUP        STATUS  
  dsk0         sliced    -            -            unknown  
  dsk1         sliced    -            -            unknown  
  dsk2         sliced    dsk2         rootdg       online  
  dsk3         sliced    dsk3         rootdg       online  
  dsk4         sliced    dsk4         rootdg       online  
  dsk5         sliced    dsk5         rootdg       online  
  dsk6         sliced    dsk6         dg1          online  
  dsk7         sliced    -            -            online  
  dsk8         sliced    dsk8         dg1          online  
  dsk9         sliced    -            -            online  
  dsk10        sliced    -            -            online  
  dsk11        sliced    -            -            online  
  dsk12        sliced    -            -            online  
  dsk13        sliced    -            -            unknown 
  dsk14        sliced    -            -            unknown
  

  The following list describes the information in the output:

  DEVICE	Specifies the disk access name assigned by the operating system.
  TYPE	Specifies the LSM disk type (sliced, simple, or nopriv).
  DISK	Specifies the LSM disk media name. A dash (-) means the device was not initialized for LSM use and therefore does not have an LSM disk media name.
  GROUP	Specifies the disk group to which the device belongs. A dash (-) means the device was not initialized for LSM use and therefore the device is not in a disk group.
  STATUS	An unused storage device is one that does not have a DISK name or GROUP name, and has a status of unknown. An unused LSM disk is one that has a DISK name, but no GROUP name and a status of online or offline.

• To display detail information about an LSM disk, enter:

  # voldisk list disk
  

  The following example displays information for an LSM disk called dsk5:

  Device:    dsk5
  devicetag: dsk5
  type:      sliced
  hostid:    servername
  disk:      name=dsk5 id=942260116.1188.servername
  group:     name=dg1 id=951155418.1233.servername
  flags:     online ready autoimport imported
  pubpaths:  block=/dev/disk/dsk5g char=/dev/rdisk/dsk5g
  privpaths: block=/dev/disk/dsk5h char=/dev/rdisk/dsk5h
  version:   n.n
  iosize:    min=512 (bytes) max=2048 (blocks)
  public:    slice=6 offset=16 len=2046748
  private:   slice=7 offset=0 len=4096
  update:    time=952956192 seqno=0.11
  headers:   0 248
  configs:   count=1 len=2993
  logs:      count=1 len=453
  Defined regions:
   config   priv     17-   247[   231]: copy=01 offset=000000 enabled
   config   priv    249-  3010[  2762]: copy=01 offset=000231 enabled
   log      priv   3011-  3463[   453]: copy=01 offset=000000 enabled
  

  The size of an LSM disk is displayed in blocks as the len= value in the public: row. 2048 blocks equal 1 MB.

See the voldisk(8) reference page for more information on the voldisk command.