Brendon wrote:I will create some sort of virtualised setup resembling yours in a VM and see if I can see similar behaviour.
I’m only aware of one other user and fortunately developer that may have sufficient hardware to replicate your scenario.
As to your process questions, no, there are no processes in the way that you state it. I dont think there is anything user tunable in terms of the priority we assign to the threads in kernel.
I guess the other thought I have is that we have no sense as to what the theoretical max throughput of zfs is on a Mac. It is unlikely to be as fast as hfs, and in my experience I’ve never seen more than 500mb/sec going to 4/5 disk pools one raiz2, one striped mirrors (on vastly different host machines). I’ll ask the guy with more hardware what he’s seen when I next see him online.
One thing we do know is that zfs drives the memory allocator very hard (manifests itself as glitchy pausy behaviour, and low ZFS FS throughput), we ported the Solaris allocator along with zfs, and it made a huge difference. But ultimately it’s backed by MacOS internals and they are quite slow under load.
All good points I hadn't considered, thanks. I have acceptable performance only because the six pools are mostly idle, two concurrent users max. Torrents really kill overall i/o, even with a separate recordsize=16k pool for that purpose. I am using tape for backup and its only running at about half speed backing up a mirrored z pair vs hfs it would hit full speed routinely. As mentioned the spiking is reduced but I still notice activity on #1 &2 slows down a download to #3 even though the download speed is 1/40 of the drive's max speed.
There was mention of drive & software cache size impact on speed. Hfs does not use a cache, can there be a way to disable caching in o3x? Seems like it creates an unnecessary step and extra i/o. For large video files a cache offers 0 benefit.
What are people going to switch to now that solaris is no longer being actively developed.. macz mentioned the oracle storage simulator, does that offer higher performance? Seems a bit clunky to have to run vmware in order to access your drives.