Will VMware write disk if I choose to allocate the disck space at the beginning?

[WaleyWang]

I want to use a 512G SSD disk specially for a virtual machine who will occupy about 400G disk space later, so I plan to allocate the space at the beginning.

Since SSD has limited write to times, so I want to make sure that VMware will not write the all the allocated disk space when create the file. Will VMware do like that?

Thanks.

[_Royce_]

I really don't see how pre-allocating would reduce the number of times VMware writes to the vmdk file.

Why are you even worrying about this?

http://betanews.com/2014/12/05/modern-ssds-can-last-a-lifetime/

Unless you have an old SSD, in which case you should replace it.

[WaleyWang]

Hi, Royce, thanks for your reply.

Sorry that I may not explain it clearly. My file will growth to 350G after maybe 1~2 years, so I plan to pre-allocate all the disk space at the begining because VMware says that it will improve the I/O performance.

While, I use SSD and sounds like that the SSD disk has limited "write to" times. And I may need try several times before successfully install the system.so I just worry that if I pre-allocate the space every time, all the space will be write and it may harmful for the disk. If it is the case, I would rater choose allocate less space at the beginning and increase it later.

Thank.

[_Royce_ · Accepted solution]

As I already stated, pre-allocating isn't going to decrease the number of writes on your SSD. The performance benefits from pre-allocation are going to be marginal at best and given that you expect a relatively slow disk usage growth I definitely wouldn't bother.

Is there any reason why you don't split the storage in to multiple drives? At least a boot drive and network share drive?

What's your backup strategy?

These are more important considerations for what you are planning.

[WaleyWang]

Thanks, Royce. Got your point! I just install an ERP system in my laptop , so no more disk available:smileylaugh:. I checked the documents, each SSD disk cell can be write about 2000~3000 times before its life ends. So it doesn't matter now. I'll pre-allocate the space at the beginning to have better I/O performance. Thank you again.

[_Royce_]

Well if it were me i wouldn't preallocate just because I don't think you will perceive any major performance benefit but by preallocating you already have to deal with a huge VMDK file.