I'm passing through a single whole disk not the 1015 controller to a hyper-v VM running FBSD 10.1 and zfs ver 5000.
writing just zeroes with dd of about 10GB to the zfs volume (created on the passed through ssd) I get about 5% fragmentation after the first pass.
The first write is at 530MB/s with a clean and "cold" system, nothing written to the disk, nothing cached.
The second write is about 460 MB/s, same dd command just to a new filename.
fragmentation at the start is about 5%
The third drops to 360MB/s or so.
when the drive is about 70 or so percent full fragmentation hits > 80%.
Any thoughts on why performance is dying so badly? I know it has to do with fragmentation but I am not sure why it fragments so quickly.
I'm going to try passing the whole controller to the vm and see what happens.
writing just zeroes with dd of about 10GB to the zfs volume (created on the passed through ssd) I get about 5% fragmentation after the first pass.
The first write is at 530MB/s with a clean and "cold" system, nothing written to the disk, nothing cached.
The second write is about 460 MB/s, same dd command just to a new filename.
fragmentation at the start is about 5%
The third drops to 360MB/s or so.
when the drive is about 70 or so percent full fragmentation hits > 80%.
Any thoughts on why performance is dying so badly? I know it has to do with fragmentation but I am not sure why it fragments so quickly.
I'm going to try passing the whole controller to the vm and see what happens.
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