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Luke404
Asked: 2014-06-19 08:02:46 +0800 CST

Should new Linux VMs under ESXi 5.5 mount their filesystems with discard option?

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When creating new Linux virtual machines using recent (>= 2014) distributions in VMware ESXi 5.5, should they mount their filesystems with the discard option ?

I make the assumption that the VM's admin does not necessarily know what is the actual underlying storage and that the VM is using whatever is the recommended "virtual controller" and I hope/suspect that if the VM sends out TRIM commands they could be useful with thin virtual disks (even if they are on non-SSD storage) or with thick virtual disks on SSD storage.

Does the discard mount option actually do something when used in an ESXi VM (eg. even if the virtual controller is a SCSI one and not a SATA one) ?

Does vSphere >= 5.5 do anything when the VM uses such discard option?

linux

1 Answers

  1. Best Answer

    As far as I know ESXi doesn't make use of TRIM commands from a VM. I havn't found anything definite or official from VMware but in a comment to a blog post I found this:

    In VMs TRIM is definetely not available, I already checked that.

    FAQ: Using SSDs with ESXi

    So it looks like mounting filesystems with the discard option won't help you.

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