Thin vs. Thick Provisioning of VMs on All-Flash Datastores
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I happen to know an individual who recently invested in a pretty nice Dell server for his business. He decided to spend a few thousand extra to get all enterprise SSDs rather than 10K SAS disks to hit an IOPs home run with his ERP system. It's OBR10 and all local storage (very nice gear). I did encourage him to get the Perc card with more cache as well. This will be a VMWare setup with the Essentials kit and a single VMFS5 datastore (nothing more than that was needed). For purposes of this thread, I am not concerned with backups.
If this individual had, for example, eight 320 GB SSDs in OBR10 on local storage with a nice Perc card to create the array, I wonder...
If you're running heavy IOP loads like SQL or Exchange (some environments are much heavier than others, of course), how much performance gain would you really get by doing thick eager provisioning for SQL / Exchange / insert application here over thin provisioning when everything is running on SSDs?
Is it best to go thick in this case if you are heavier write than read?
Do the guidelines of when to use thin vs. thick eager change because of the speed of the storage and possibly allow you to save some storage space by sticking with thin provisioned disks?
I've been thinking about it and don't have a good answer as to some guidelines for using thin vs. thick when talking about SSDs. I wanted to hear from some experts out there. Any help is much appreciated.
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I'm totally in the camp of thin provisioning nearly everything. You are already pushing the controller probably past its performance limits, the minuscule difference in performance between thin and thick provisioning is unlikely to be measurable on this system. You are into the realm of driving a Ferrari F40 and trying to figure out which paint colour makes for a smoother surface.
At worst, if you really fear for the database, thick provision that one disk and thin everything else. But only if the database will grow regularly, but predictably.
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@NetworkNerd said:
Is it best to go thick in this case if you are heavier write than read?
Write versus Read isn't an issue, it's growth that causes latency in thin provisioned systems, not writes.
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@NetworkNerd said:
Do the guidelines of when to use thin vs. thick eager change because of the speed of the storage and possibly allow you to save some storage space by sticking with thin provisioned disks?
Yes, SSDs change things a bit because capacity is lower and performance is higher. So the ratios of things shift.
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@NetworkNerd said:
I've been thinking about it and don't have a good answer as to some guidelines for using thin vs. thick when talking about SSDs. I wanted to hear from some experts out there. Any help is much appreciated.
No question that SSDs really shake things up in this case. The underlying factors still remain but the vast difference in speed and capacity and cost make the decision matrix lean heavily towards thin provisioning. Especially since you have solved so much of the general performance issues.
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The only real reason I would see for not going with thin provisions would be poor planning and then running out of space. otherwise I don't see a issue or reason not to go with it if it's planned well.
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@thecreativeone91 said:
The only real reason I would see for not going with thin provisions would be poor planning and then running out of space. otherwise I don't see a issue or reason not to go with it if it's planned well.
That is a surprisingly common fear that I have heard.
