We are experiencing weird write performance problems with Western Digital 4[ ]TB SAS drives (WD4001FYYG) under FreeBSD. Read performance is fine but (sequential) write performance does not get above 10-14 MB/s which is way below the expected value of 100-150 MB/s. This was tested by doing a dd with blocksize 1 MB to the disk device on an idle disk.
Our setup is as follows:
FreeBSD 9.1
LSI 9211-4i controller
3x WD 4 TB SAS drives
2x Kingston V300 SSD drives (boot/OS partition)
SuperMicro X9DRI-F-B mainboard
The problem does not seem to be with the drives themselves as their write performance under Linux is fine (150 MB/s).
Latest drivers have been installed and we performed the following additional tests to analyse this problem:
Right now we are pretty much stumped why we get such a dreadful performance. All the hardware manufacturers list everything as being compatible (controller, drives and OS). Is there anyone here that has an idea what might be going on or how this could be fixed?
Our setup is as follows:
FreeBSD 9.1
LSI 9211-4i controller
3x WD 4 TB SAS drives
2x Kingston V300 SSD drives (boot/OS partition)
SuperMicro X9DRI-F-B mainboard
The problem does not seem to be with the drives themselves as their write performance under Linux is fine (150 MB/s).
Latest drivers have been installed and we performed the following additional tests to analyse this problem:
- Different SAS disk: tested a Seagate SAS disk, this performed to specs (write speeds 150 MB/s)
- Test with SATA WD disk: We tested with a SATA Western Digital RE drive, this performs fine too (write speeds ~150 MB/s)
- Different controller driver versions: Installed the latest version but also older versions, problem persisted on WD drives
- Different controller: Tried a different LSI SAS controller, worked fine with other drives but not with WD drives
- Different FreeBSD version: Installed FreeBSD 8, which did not make a difference
Right now we are pretty much stumped why we get such a dreadful performance. All the hardware manufacturers list everything as being compatible (controller, drives and OS). Is there anyone here that has an idea what might be going on or how this could be fixed?