On 03/07/2009, at 10:37 PM, Victor Latushkin wrote:
Slog in ramdisk is analogous to no slog at all and disable zil (well, it may be actually a bit worse). If you say that your old system is 5 years old difference in above numbers may be due to difference in CPU and memory speed, and so it suggests that your Linux NFS server appears to be working at the memory speed, hence the question. Because if it does not honor sync semantics you are really comparing apples with oranges here.
The slog in ramdisk is in no way similar to disabling the ZIL. This is an NFS test, so if I had disabled the ZIL, writes would have to go direct to disk (not ZIL) before returning, which would potentially be even slower than ZIL on zpool.
The appearance of the Linux NFS server appearing to perform at memory speed may just be the BBWC in the LSI MegaRaid SCSI card. One of the developers here had explicitly performed tests to check these similar assumptions and found no evidence that the Linux/XFS sync implementation to be lacking even though there were previous issues with it in one kernel revision.
cheers, James _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
