iTechNote

Roch Bourbonnais at Kernel Performance Engineering, Sun Microsystems reckons ZFS is not quite ready for the prime time. The result shows an increasing better performance on each ZFS build and is not far from a super tuned UFS.

To achieve acceptable performance levels:

The latest ZFS code base. ZFS improves fast these days. We will need to keep tracking releases for a little while. The current OpenSolaris release as well as the upcoming Solaris 10 Update 3 (this fall), should perform for these tests, as well as the Build 44 results shown here.

UFS/DIO : 100 %
UFS : xx no directio (to be updated)
ZFS Best : 75% best tuned config with latest bits.
ZFS S10U2 : 50% best tuned config.
ZFS S10U2 : 25% simple tuning.

UFS (with DIO) has been heavily tuned over the years to provide very good support for DBMS. We are just beginning to explore the tweaks and tunings necessary to achieve comparable performance from ZFS in this specialized domain. We knew that running a DBMS would be a challenge since, a database tickles filesystems in ways that are quite different from other types of loads.

The comparison was on a Niagara T2000 (8 cores @ 1.2Ghz, 4 HW threads or strands per core) with 130 @ 36GB disks attached in JBOD fashion. Each disk was partitioned in 2 equal slices, with half of the surface given to a Solaris Volume Manager (SVM) onto which UFS would be built and the other half was given to ZFS pool.

JBOD: This is an acronym for ‘Just a Bunch Of Disks’. Most disk controllers don’t have any RAID functionality built into them. In these cases, the Operating System sees the disk drives connected to the controller as JBOD. In addition, many RAID controllers default to a JBOD configuration before being configured for RAID. It should be noted that some manufacturers use the term JBOD to refer to a Spanned or Concatenated array.

DIO: directio, a file access method in which the system behaves as though the application is not going to reuse the file data in the near future. In other words, the file data is not cached in the system’s memory pages.

via Blogs.sun.com