Hi Scott, Scott Williamson wrote: > You seem to be using dd for write testing. In my testing I noted that > there was a large difference in write speed between using dd to write > from /dev/zero and using other files. Writing from /dev/zero always > seemed to be fast, reaching the maximum of ~200MB/s and using cp which > would perform poorler the fewer the vdevs.
You are right, the write benchmarks were done with dd just to have some "bulk" bulk figures since usually zeros can be generated fast enough. > > This also impacted the zfs send speed, as with fewer vdevs in RaidZ2 the > disks seemed to spend most of their time seeking during the send. > That seems a bit too simplistic to me. If you compare raidz with raidz2 it seems that raidz2 is not too bad with fewer vdevs. I wish there was a way for zfs send to avoid so many seeks. The << 1 TB file system is still being zfs send, now close to 48 hours. Cheers Carsten PS: We still have a spare thumper sitting around, maybe I give it a try with 5 vdevs _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
