VMware Communities
natieo
Contributor
Contributor

Poor disk performance on guest (small file I/O)

VMware Workstation

12.5.7 build-5813279

  • Host only has one drive, 500GB Samsung 850 EVO SSD, so guest shares host drive (not an option at the moment to put them on a separate drive).
  • Guest is configured with a pre-allocated non-split drive (one big file).
  • No AV software beyond windows defender, which is excluding the VM folder entirely.
  • VMware Tools installed and running.
  • Windows 10 everywhere.

The disk speed on the guest is really poor for certain things, namely many small file operations. This is confirmed by CrystalDiskMark benchmarks:

VMware_Workstation_SSD_Speed.jpg

Those tests are described here:

  • Seq Q32T1: Sequential (Block Size=128KiB) Read/Write with multi Queues & Threads
  • 4K Q32T1: Random 4KiB Read/Write with multi Queues & Threads
  • Seq: Sequential (Block Size=1MiB) Read/Write with single Thread
  • 4K: Random 4KiB Read Write with single Queue & Thread

So the sequential tests with larger files have pretty good parity between the VM host and guest, but the 4k random tests are WAY slower on the guest! This is exactly the sort of thing we need to be fast -- we're building and running tests that do lots of small file I/O.

I've been reading and trying various tweaks for two days now with no luck. Anyone have any ideas on getting better performance out of the VM?

Thanks,

Nate

Reply
0 Kudos
1 Reply
parmarr
VMware Employee
VMware Employee

Hello,

Please see KB below for assistance:

Troubleshooting hosted disk I/O performance problems (1008885) | VMware KB

Sincerely, Rahul Parmar VMware Support Moderator
Reply
0 Kudos