Unique to HP's product is Hot-Plug RAID Memory. The standard server ships with 5 GB of ECC SDRAM, but only 4 GB are available to the OS. The fifth module is a hot-swap spare that takes over if any other RAM modules fail or produce errors. Rather than use a mirrored RAM configuration, Hot-Plug RAID requires a mere 25 percent increase in memory.
If the server is running Linux or the upcoming Windows 2003 Server, memory can be hot-added to a running system. If you are upgrading from the standard 5 GB to the maximum 64 GB, you must remove a memory bank, replace or add DIMM modules on that bank, and reinstall the bank. The OS will allocate the additional memory.
The DL740 has six available 64-bit, 100-MHz hot-pluggable PCI-X slots spread over three buses, which ensures that slower cards don't bring down the entire bus and high-bandwidth cards--Fibre Channel or additional Gigabit Ethernet cards--get the capacity they need.
RAID Control
For storage, the DL740 features a four-drive, internal hot-swap Ultra3 SCSI drive cage. The server I tested came with four 36.4-GB 15,000 RPM SCSI drives, but the maximum internal capacity is 587.2 GB, using 146.8-GB drives. The DL740 comes standard with the 5i RAID controller with 32 MB of cache embedded on the main board; my test unit came with HP's optional 5312 RAID controller, which sports 128 MB of cache memory and two external connectors. I tested both controllers with Intel's IOmeter. The 5312 controller's performance was about 18 percent higher than that of the 5i, primarily because of the additional cache. However, both RAID controllers exhibited good performance.