By hiding the write latency of disks and thereby enabling the use of economical, high-capacity drives, Logzilla, a key component of the ZFS Hybrid Storage Pool, can accelerate synchronous writes, blogger Adam Leventhal observes, conceding at the same time the role played by the fast SAS and SATA SSDs from STEC in the Sun Storage 7000 series. He adds that using SAS-attached SSDs is a simpler and more reliable, though slower, clustering solution than the traditional PCI-attached DRAM device, however.

Leventhal writes about his experiences in testing the X1 from DDRdrive, which is a 4GB NV-DRAM card with flash to back up storage. The X1, though too large to fit in the half-height DIMM slots in Sun/Oracle systems, has its own DC power lead, which liberates the device from dependence on batteries or super-capacitors.

In his tests, Leventhal found that the DDRdrive X1 performed a 4K write in about 51 microseconds, though he also found that the SSD outperformed the X1 in transfer sizes over 32 KB. Further refinements by DDRdrive have improved performance of the X1, he notes.

Even though the X1 will not be a component in the 7000 series, Leventhal concludes, ZFS uses that do not require clustering and that feature external backup power are excellent situations in which X1 can play a role in accelerating write performance in ZFS, a role that warrants considering its employment in such situations.

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