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I have read a lot of information on using SSD drives in virtualization environment and the possible problems with not supported TRIM command. I fully understand what the TRIM is, what the problems with passing TRIM down to the drive are and so on.

What I didn't find is clear answer on the question: "is there any way to use SSD drive in guest OS without affecting its performance (associated with lack of the TRIM command)".

For example.. is the solution to connect the SSD drive in RAW mode to the guest machine? If not, why? Are there any other harder to implement options just to "make it right".

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  • I've thought about building a new machine and putting 32GB RAM in it so that I could RAM drive load my VM's into that. But it seems cheaper to buy a 500GB SSD and let VM read and write it's vmdk files. Just manually run Intel's TRIM tool once a week and you'll be fine I would think.
    – pcunite
    Commented May 4, 2012 at 22:50
  • I think it will work (trimming once month) but I was hoping for some answers from people that have tested this approach and can share their input on the topic.
    – Krzysztof Szynter
    Commented Jun 10, 2012 at 18:42
  • I've purchased a Crucial M4 256GB SSD for VM use. I have already written to every sector and it seems to be working very well. TRIM works when a file is marked for deletion. With vmdk files this is never happening. However, who cares! It is still fast. If you want to claim space you can always compact the vmdk. Here is an interesting link: lifeofstu.com/?p=75
    – pcunite
    Commented Jul 30, 2012 at 3:11

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I currently run VM Workstation 8 on a set of 3 OCZ Vertex 3 240 Max IOP SSDs in a RAID 0 set. Performance is great. Since there is no TRIM in RAID I just leave about 100Gb unused so that garbage collection can still take place. Lack of TRIM has never been a factor and I'm running about 8 servers including an iSCSI server. With iSCSI I just serve up disk images and the performance is super. Clustering is very doable, even on a good laptop. Running VMware ESXi is also very doable. SSD makes it happen.

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TRIM is used to explicitly tell SSD which blocks are free for 'garbage collection'. If you directly attach SSD to a VM guest and let guest handle TRIM, you will accomplish this. However, it is my understanding that if you keep your vmdk files on a OS/FS that supports TRIM, then you should be all set. So, Vmware Workstation on Win 7 which supports TRIM should be good enough for longevity and performance of your ssd drive.

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