A highly available and expandable, rack-dense, 1U dual-socket SMP server, for application
serving in Web environments
Please see the Legal Information section for important notices and information.
5
DDR II ECC Fully Buffered Memory with Chipkill Protection
The x3550 supports up to
32GB
of memory in
8
DIMM sockets. Some models include
two
512MB
DIMMs standard, while others ship with
two 1GB
DIMMs. The x3550 uses
PC2-5300
fully-buffered
double data rate II (DDR II) memory (operating at
667MHz
) for faster access, and
provides Active Memory features, including advanced
Chipkill
memory protection, for
up to 16X
better error correction than standard ECC memory.
The fully buffered memory in the x3550 provides up to
triple
the memory bandwidth (up to
21.3GBps
in
four
channels of PC2-5300 fully-buffered DIMMs vs. a maximum of 6.4GBps in two
channels of unbuffered PC2-3200 memory and up to
double
the system memory capacity (
8
DIMMs x
4GB
) of the predecessor x336 server (8 DIMMs x 2GB). By performing reads and writes
simultaneously, it eliminates the previous memory read-to-write blocking latency. In addition, it
also offers innovative data reliability and security features to help improve data integrity, including
enhanced CRC protection, data retry on error detect and buffer registers for improved fault
isolation.
For increased availability, the x3550 offers two additional (but mutually exclusive) levels of IBM
Active Memory protection: online
memory mirroring
, and
online hot-spare
memory
.
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. Mirroring can be accomplished with multiples
of
four
DIMMs (one pair per memory channel). Up to
16GB
(four 4GB DIMMS) of memory is
available for use with mirroring enabled. (
Note:
Due to the double writes to memory, performance
is affected.)
When
online
hot-spare memory
is enabled, using single and/or dual-rank DIMMs
one rank
is set
aside per branch as online spares in case one of the other ranks fails.
The spare rank must have
capacity at least that of the largest active rank.
Up to
24GB
(using 8
single
-rank 4GB DIMMs) or
28GB
(using 8
dual
-rank 4GB DIMMs) of memory is available when the hot-spare feature is
active. (The lowest-numbered rank of those with the highest capacity in each branch is used for
the hot-spares.)
Either of these features requires operating system support.
When multiples of four DIMMs (4 or 8) are installed, the x3550 operates in
four-way interleaved
mode, for higher performance. When only
two
DIMMs are used, the system defaults to
two-way
interleaved
mode.
DIMMs must be installed in pairs. Memory is available in kits consisting of
two
512MB
,
1GB, 2GB
or
4GB
DIMMs.
Drive Bays
The x3550 contains
either
two
or
four
drive bays in all, depending on the model. Some models
offer
two
3.5-inch
bays that support
hot-swap SAS
or
simple-swap SATA II
drives. This
enables up to two slimline (1.0") drives to be installed, totaling up to
600GB
(SAS) or
2TB
(SATA).
Other models feature
four 2.5-inch
bays that support
hot-swap SAS
drives totaling up to
587.2GB
.
Hot-swap drives may be inserted or removed through the front of the server without powering off
the system. Simple-swap 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/8X
4
speed (ultraslim, 0.5”) CD-RW/DVD-ROM Combo drive with an IDE interface
ships standard in all x3550 servers. No diskette drive is supplied with any model; an external
USB floppy drive may be used, if needed.
4
Variable read rate. Actual playback speed varies and is often less than the maximum possible.
