Dell PowerEdge T410 Deploying UEFI-Aware Operating Systems on Dell PowerEdg - Page 10

expected. Dell recommends that you contact your application vendors for all mission‐critical applications to ensure they work in the UEFI environment. Limitations This section explains potential problems which may occur while installing a UEFI‐aware operating system and how to avoid them. Large Operating System Partitions An operating system installer relies on disk controller firmware to perform disk read/write functions prior to the disk driver is available. Certain legacy disk controllers use older firmware (such as Interrupt 0x13 handlers) to execute read/write functions in UEFI mode and do not provide native access disks in UEFI mode. The UEFI layer provides the abstraction driver to access the disks using the old firmware. The most notable restriction is that the legacy interrupt 0x13 functions are unable to access logical block addresses higher than 2 terabytes (TB). For this reason, Dell strongly recommends using a partition or virtual disk smaller than 2TB for the partition where the operating system resides. Failure to use a partition size of less than 2TB for the operating system virtual disk may cause undesired behavior and will eliminate the inherent GPT partition redundancy. Data partitions (non‐system partitions) can be larger than 2TB since the disk driver is available when the operating system accesses these partitions. Third Party Imaging Utilities UEFI uses a partitioning scheme known as a GPT. This scheme assigns a Globally Unique Identifier (GUID) to each partition in a disk. Be aware that imaging utilities (such as Norton Ghost) need to re‐create the GPT in order to have unique GUIDs for partitions which are copied from one disk to another. Otherwise different disks will use the same GUID for multiple partitions, which may cause conflicts for software which uses the GUIDs to distinguish each partition. Transferring Hard Disks UEFI Boot Options are stored in non‐volatile memory on a system. When an operating system installer executes, it creates a boot option for the operating system in the system's non‐volatile memory. If the hard disk which contains the operating system is removed and transferred to another system, this new system will not have the boot option in its non‐volatile memory, and a user will not be able to boot to the operating system. Dell has addressed this problem by keeping a copy of the operating system boot option on the hard disk with the operating system. When the hard disk is transferred to another Dell system, the system uses the copy of the operating system boot option to create a boot option in its non‐volatile memory. This allows a user to boot to the operating system. The process is automatic; no user interaction is necessary to create the boot option on the second system. UEFI Legacy Boot Controllers The UEFI layer provides the abstraction driver to access the disks using the interrupt 0x13 functions. The following Dell UEFI Legacy boot controllers operate using legacy abstraction supported in UEFI mode: Dell PERC 6/i Dell SAS 6/iR Future controllers will provide native UEFI drivers. Page 8