IBM 250000, 190000 specifications Drive Bays, Disk Controllers

Leadership enterprise server with significantly lower cost of ownership in a highly available and expandable, rack-dense, 1U dual-socket server

This new processor design comes with some trade-offs in memory capacity, performance, and cost: For example, greater memory capacity comes with lower memory speed. Alternatively, it is possible to achieve the same memory capacity at lower cost but at a lower memory speed.

Regardless of memory speed, the Xeon 5500 platform represents a significant improvement in memory bandwidth over the previous Xeon 5400 platform. At 1333MHz, the improvement is almost 500% over the previous generation. This huge improvement is mainly due to the dual integrated memory controllers and faster DDR-3 1333MHz memory. Throughput at 800MHz is 25 gigabytes per second (GBps); at 1066MHz it’s 32GBps; and at 1333MHz it’s 35GBps. This improvement translates into improved application performance and scalability.

Memory interleaving refers to how physical memory is interleaved across the physical DIMMs. A balanced system provides the best interleaving. A Xeon 5500 processor-based system is balanced when all memory channels on a socket have the same amount of memory.

A memory rank is simply a segment of memory that is addressed by a specific address bit. DIMMs typically have 1, 2 or 4 memory ranks, as indicated by their size designation.

•A typical memory DIMM description is 2GB 4Rx8 DIMM

•The 4R designator is the rank count for this particular DIMM (R for rank = 4)

•The x8 designator is the data width of the rank

It is important to ensure that DIMMs with appropriate number of ranks are populated in each channel for optimal performance. Whenever possible, it is recommended to use dual-rank DIMMs in the system. Dual-rank DIMMs offer better interleaving and hence better performance than single-rank DIMMs. For instance, a system populated with six 2GB dual-rank DIMMs outperforms a system populated with six 2GB single-rank DIMMs by 7% for SPECjbb2005. Dual- rank DIMMs are also better than quad-rank DIMMs because quad-rank DIMMs will cause the memory speed to be down-clocked.

Another important guideline is to populate equivalent ranks per channel. For instance, mixing one single-rank DIMM and one dual-rank DIMM in a channel should be avoided.

Note: It is important to ensure that all three memory channels in each processor are populated. The relative memory bandwidth decreases as the number of channels populated decreases. This is because the bandwidth of all the memory channels is utilized to support the capability of the processor. So, as the channels are decreased, the burden to support the requisite bandwidth is increased on the remaining channels, causing them to become a bottleneck.

For increased availability, the x3550 M2 offers an additional (but mutually exclusive) level of IBM Active Memory protection: online memory mirroring..

Memory mirroring works much like disk mirroring. The total memory is divided into two channels. Data is written concurrently to both channels. If a DIMM fails in one of the DIMMs in the primary channel, it is instantly disabled and the mirrored (backup) memory in the other channel becomes active (primary) until the failing DIMM is replaced. One-half of total memory is available for use with mirroring enabled. (Note: Due to the double writes to memory, performance is affected.)

Mirroring is handled at the hardware level; no operating system support is required.

DDR-3 memory is available in 1GB, 2GB, 4GB and 8GB DIMMs. DIMMs are installed individually (not in pairs).

Drive Bays

The x3550 M2 contains six drive bays in all. Hot-swap drives may be inserted or removed through the front of the server without powering off the system. Simple-swap solid-state drives can be inserted or removed through the front of the server as well; however, the system power must first be turned off.

For additional storage, a direct-attach, NAS or SAN external expansion option can be added, using an optional controller.

A 24X/24X/24X/8X5 speed (ultraslim, 0.5”) CD-RW/DVD-ROM Combo drive with an IDE interface ships standard in all x3550 M2 servers. No diskette drive is supplied with any model; an external USB floppy drive may be used, if needed.

Disk Controllers

All SAS-equipped x3550 M2 models include an integrated hardware based ServeRAID-BR10i SAS/SATA controller. This controller supports up to six internal SAS, SATA or solid-state drives.

5Variable read rate. Actual playback speed varies and is often less than the maximum possible.

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