IBM Cites 'Breakthrough' in Phase-Change Memory Development (
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Every so often, the IT world gets news of a "breakthrough" in new
storage media research, and this week it was IBM's turn to announce one
in relation to a possible long-term replacement for NAND flash
solid-state disks.
Big Blue on June 30 revealed that its Zurich-based PCM (phase-change
memory) research unit has produced 90-nanometer-size chips that can
store multiple bits of data per cell over time without the data becoming
corrupted. This is a problem that has been nagging development since
IBM started this project nearly 10 years ago.
Previously, each PCM
cell
was able to hold a single data bit, and even those became lost or
corrupt at
unpredictable times. IBM said this latest development can lead to
solid-state chips that can store as much data as NAND flash disks (which
now are up to
1TB in capacity) but feature about 100 times the data movement speed, to
go
with a much longer life span.
NAND flash is inherently
slowed down by so-called erase-write cycle limitations. This is because NAND
flash requires that data first be marked for deletion before new data is
written to the disk, which slows the process considerably. PCM does not require
erase-write cycles.
Thus, the extra erase-write
activity causes NAND flash performance to degrade faster and, over time, wear
out the disk. Typically, NAND flash disk life spans range from 5,000 to 10,000
write cycles in consumer disks and up to 100,000 cycles in enterprise-class
disks.
In contrast, PCM can handle
up to an estimated 5 million write cycles, IBM and Intel (through its
PCM-dedicated Numonyx arm) both contend.
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