# ZFS performance under ESXi



## MightyMike (Aug 12, 2012)

I recently migrated a FreeNAS 8 server under ESXi to a plain FreeBSD 9. However, the performance is (very)far from matching up. The performance caps at ~1.5MB/s on writes.

The setup is as followed
-Athlon II X4 630 (Virtualized by VMWare ESXi)
-3GB RAM dedicated to the FreeBSD server
-RAID-Z on 6x 2TB HDD mapped via RDM to the FreeBSD server

I have tried the following to try to boost the performance back to acceptable levels:
- setting zfs.cache_flush_disable
- disabling the ZIL
- re-enabling ZFS prefetch

Any ideas to get the performance back to acceptable levels?


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## Crest (Aug 12, 2012)

Run FreeBSD on the bare metal?


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## MightyMike (Aug 12, 2012)

Crest said:
			
		

> Run FreeBSD on the bare metal?



I needed the virtualization but trying FreeBSD on the bare metal was my next step. What baffles me however, is that FreeNAS managed decent performance on the same ESXi host.


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## Savagedlight (Aug 15, 2012)

How did you partition the disks?
The reason I ask is that ZFS have severe performance problems with 'advanced format' drives if they lie about their sector size. Their sector size is 4k, but some of them state it's 512B. ZFS believes them, and performance suffers due to misalignment.

You can take a look here (shameless plug) for info on how I deal with this problem.


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