I apologize if this has been addressed countless times, but I have searched & searched and have not found the answer.
I'm rather new to ZFS and have learned a lot about it so far. At least one thing confuses me, however. I've noticed that writes to the boot disk in OpenSolaris (i.e. pool rpool) are significantly slower than a write on the same system to an identical drive with a pool on an identically configured slice. If the two drives are configured in every way identically, even inside VirtualBox using virtual drives, the non-boot disk always outperforms the boot disk by up to 4-5x, depending on the computer. My newest computer shows the smallest performance difference (less than 30%), I suppose because it is the fastest system with the fastest drives. I did notice that the apparently better performing pools seem to be taking advantage of the ZFS cache, because you can see the activity light for long after the OS reports it's finished. I'm testing with files far larger than the disk's own cache. I see the same consistently reported (not real) performance of ~140MB/s even on USB powered external drives. Quite an impossible number for USB! Is it the overhead of being the boot drive with root's ZFS pool? Does a ZFS root not use ZFS's caching? Since this is easily reproduced in VirtualBox (with lower numbers), it can't be the drive's own cache that aids this. It would be nice to have better performance on the default rpool when you have only two disks and want a mirror, but the OpenSolaris installer doesn't give you any options. I still like OpenSolaris anyway! Thanks, and I hope I made sense here. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
