Users Guide

• Rebuilding data — An failed physical disk that is used by both redundant and nonredundant virtual disks cannot be rebuilt. Rebuilding a
failed physical disk in this situation requires deleting the nonredundant virtual disk.
• Disk group concept consideration for S110 — Disk grouping is a logical grouping of disks attached to a RAID controller on which one or
more virtual disks are created, such that all virtual disks in the disk group use all of the physical disks in the disk group. The current
implementation supports the blocking of mixed disk groups during the creation of logical devices.
Physical disks are bound to disk groups, therefore, there is no RAID level mixing on one disk group.
Storage Management Server implements the disk group concept during virtual disk creation. Functionally, after a group of physical disks is
used to create their first virtual disk, unused space in the disk is used only to expand the virtual disk, or create new virtual disks in the
unused space. The virtual disks have identical RAID level.
Also, existing mixed configuration is not affected. However, you cannot create mixed configurations.
You can read or write to the virtual disks, rebuild, and delete the disks.
You cannot create virtual disks on a set of disks migrated from earlier software RAID versions and configured with multiple RAID levels.
Considerations For Hot Spares On PERC S100 And PERC
S300 Controllers
For the PERC S100 and PERC S300 controllers, a hot spare is assigned to a virtual disk. When a physical disk fails, only the portion of the
physical disk containing the virtual disk is rebuilt onto the hot spare. Data or space on the physical disk is not included in the virtual disk are
not rebuilt.
On the PERC S100 and PERC S300 controllers, individual physical disks may be included in more than one virtual disk. Assigning a portion
of a physical disk to a virtual disk does not preclude the remaining portion of the physical disk from being used by other virtual disks. Only
the virtual disks to which the hot spare is assigned are rebuilt. When using Storage Management, a disk that is assigned as a hot spare on
a PERC S100 and PERC S300 controller cannot be used as a member of a virtual disk.
Virtual Disk Considerations On Systems Running Linux
On some versions of the Linux operating system, the virtual disk size is limited to 1TB. Before creating a virtual disk that is larger than 1TB,
you should make sure that your operating system supports this virtual disk size. The support provided by your operating system depends
on the version of the operating system and any updates or modifications that you have implemented. In addition, you should investigate
the capacity of your peripheral devices to support a virtual disk that is larger than 1TB. For more information, see your operating system
and device documentation.
Number Of Physical Disks Per Virtual Disk
There are limitations on the number of physical disks that can be included in the virtual disk. These limitations depend on the controller.
When creating a virtual disk, the controllers support some stripes and spans (methods for combining the storage on physical disks). Since,
the number of total stripes and spans is limited, the number of physical disks that can be used is also limited. The limitations on stripes and
spans affect the possibilities for concatenation and RAID levels as follows:
• Maximum number of spans affects RAID 10, RAID 50, and RAID 60.
• Maximum number of stripes affects RAID 0, RAID 5, RAID 50, RAID 6, and RAID 60.
• Number of physical disks in a mirror is always 2. This property affects RAID 1 and RAID 10.
If RAID 50 and RAID 60, you can use a greater number of physical disks than is possible for other RAID levels. RAID 10 on a SAS controller
with firmware version 6.1 can use a maximum of 256 physical disks. However, the number of connectors on the controller imposes
limitations on how many physical disks can be included in a virtual disk when using RAID 10, RAID 50, or RAID 60. This is because only a
limited number of physical disks can be physically attached to the controller.
For information about the maximum number of physical disks supported by a virtual disk, see the virtual disk specifications for the
controller in Supported Features.
Number Of Virtual Disks Per Controller
There are limitations on the number of virtual disks that can be created on the controller. For information about the maximum number of
virtual disks supported by a controller, see the virtual disk specifications for the controller in Supported Features.
Virtual Disks
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