To vSAN or not to vSAN?



  • The basics of my issue is that we are a small company and most stereotypes for spending and budgets apply.

    We have DAS on our hosts and if a host goes down we lose whatever is on it. I've been looking into starwind but I'm wary of jumping from one wreck to another. Specially because our hosts have finally been stable lately. A Dell R720 is our BEST host with most of them being R610's. We have all the DAS disk as well as a broken VNX that I can pull disk from so I think I have capacity. My worry is that when a box goes down now it only takes down what's on it. If we have unsupported vSAN troubles (because I doubt I can get business to pay for support) then EVERYTHING is down. So I kinda want some thoughts or insights from anyone who has done it before.

    Saying it would be unsupported would maybe cover this, but to clarify I would set it up as a storage appliance and not run VMs on it. Specially since I'd be limited to 3 nodes that way. My thoughts are Dell R620's with fiber cards to a 10gb switch for connectivity. and raid cards for disk. I may be able to weasel my way into two 710's which would have more room for expansion.

    This post got long quick but I wanted as much info as possible.
    TL:DR - My equipment is old and busted. Should I use to to run vSAN?



  • Here is the real question... why run any shared storage whatsoever? Raising costs, and raising risks. The current scenario tells us that reliability isn't the top concern (and it rarely is, so that's normal.) Why we "be weird", just run normal stand alone servers and voila, everything is solved.



  • @Shaman06 said in To vSAN or not to vSAN?:

    TL:DR - My equipment is old and busted. Should I use to to run vSAN?

    Starwind is the best vSAN maker, by a long shot, IMHO. Nothing is going to be more reliable, if you need shared storage.

    So the first question is...

    Do you need shared storage? I'm guessing "no", but we need to see.

    If so, then vSAN at this size (and budget) is the only option.



  • Seeing as how we are functional now, I am fairly confident in saying that we don't "need" shared storage. We do have some VMs that are getting large however (lets say 2TB and up for maybe a half dozen boxes, a dozen tops) and due to either resources or stability issues, I feel like I've been moving them a lot. Whether they are live migrated or shut down it seems like it's a minimum of a full day to do anything with them.

    The other gain from shared storage is faster disk but that doesn't really count since it will take time but if we don't use the shelves for vSAN we can use them for DAS. Too many of our shelves (in my opinion) are slow MD1000's with Sata drives. So they are immediately down to 1.5.



  • @Shaman06 said in To vSAN or not to vSAN?:

    The other gain from shared storage is faster disk

    That's not true, it's slower. Shared storage always comes at a price.



  • For speed, you want simple, local, RAID drives. If speed of that magnitude really matters. Nothing is faster than local NVMe.

    Anything shared, remote, or replicated has to lose speed to accomplish any of those factors.



  • Sorry, I meant it's faster because the shelves are newer and are double the speed. Again though, I said that didn't really count since if we don't do shared storage I can repurpose those as DAS. Much of the DAS is 3GB speeds (or half that since its sata) and I have at least 2 newer shelves that are 6GB and SAS so I'll get the full pipe.

    "Speed" is relative in this instance and it doesn't need to be the fastest thing on the market, I just need it to not be so slow. I have a few existing RAIDs from before I started that are large (18TB or larger) that are sata on old shelves so they are running at 1.5GB speeds and I assume their pipes get full long before the disk does.

    By the way, thanks for the fast responses. 🙂



  • @Shaman06 said in To vSAN or not to vSAN?:

    Sorry, I meant it's faster because the shelves are newer and are double the speed. Again though, I said that didn't really count since if we don't do shared storage I can repurpose those as DAS. Much of the DAS is 3GB speeds (or half that since its sata) and I have at least 2 newer shelves that are 6GB and SAS so I'll get the full pipe.

    "Speed" is relative in this instance and it doesn't need to be the fastest thing on the market, I just need it to not be so slow. I have a few existing RAIDs from before I started that are large (18TB or larger) that are sata on old shelves so they are running at 1.5GB speeds and I assume their pipes get full long before the disk does.

    By the way, thanks for the fast responses. 🙂

    Don't confuse the transfer speed on the interface (SATA/SAS) with the transfer speed of the mechanical disk.

    In almost all cases the mechanical disc is the bottleneck.



  • True, but I would hope a 15 drive RAID6 would offer enough read speed to fill 1.5GB. Not all of these are mechanical either. I know I have at least two 1.5GB pipes full of SSDs. Why my predecessor wasted the money on SSDs for that I'm not sure. Probably just assumed that SSD is ALWAYS faster and what you want if you can get it.



  • @Shaman06 said in To vSAN or not to vSAN?:

    Sorry, I meant it's faster because the shelves are newer and are double the speed.

    Compared to the internal drive slots?



  • @Shaman06 said in To vSAN or not to vSAN?:

    True, but I would hope a 15 drive RAID6 would offer enough read speed to fill 1.5GB. Not all of these are mechanical either. I know I have at least two 1.5GB pipes full of SSDs. Why my predecessor wasted the money on SSDs for that I'm not sure. Probably just assumed that SSD is ALWAYS faster and what you want if you can get it.

    That's definitely fill 1.5GB, lol.



  • @scottalanmiller said in To vSAN or not to vSAN?:

    Compared to the internal drive slots?

    Our current shelves are 1.5GB and we have some newer shelves that will run at 6GB.



  • @Shaman06 said in To vSAN or not to vSAN?:

    TL:DR - My equipment is old and busted. Should I use to to run vSAN?

    No, it's too late. You are on a sinking ship and it's leaking. You need to worry about finding something else that can keep you afloat before you drown.



  • I'm sorry, this, just sounds like a train wreck even before the train has departed the station!



  • @Shaman06 said in To vSAN or not to vSAN?:

    TL:DR - My equipment is old and busted.

    What's making them want to keep running on it and investing your expensive time into supporting very cheap old gear (cheap now that it is old.)



  • @Shaman06 said in To vSAN or not to vSAN?:

    Seeing as how we are functional now, I am fairly confident in saying that we don't "need" shared storage. We do have some VMs that are getting large however (lets say 2TB and up for maybe a half dozen boxes, a dozen tops) and due to either resources or stability issues, I feel like I've been moving them a lot. Whether they are live migrated or shut down it seems like it's a minimum of a full day to do anything with them.

    The other gain from shared storage is faster disk but that doesn't really count since it will take time but if we don't use the shelves for vSAN we can use them for DAS. Too many of our shelves (in my opinion) are slow MD1000's with Sata drives. So they are immediately down to 1.5.

    I don't know what you are using, but maybe you can see about chiftimg redundancy up a layer from hardware to software/application layer. Perhaps enabling DFS-R if you are that direction or native SQL options for databases, or even multimaster software options. This way if hardware goes down, maybe your business critical services and data can still be accessible.



  • @scottalanmiller said in To vSAN or not to vSAN?:

    What's making them want to keep running on it and investing your expensive time into supporting very cheap old gear (cheap now that it is old.)

    The environment is split. Our "prod" is almost brand new and uses an NVMe vSAN. As long as that environment is quick and running, very little care is given to our "ops" environment. To the business's credit, they seem to acknowledge that it's old hardware and don't seem to care a ton about downtime. As an IT professional, I loathe unscheduled downtime.



  • @Shaman06 said in To vSAN or not to vSAN?:

    @scottalanmiller said in To vSAN or not to vSAN?:

    What's making them want to keep running on it and investing your expensive time into supporting very cheap old gear (cheap now that it is old.)

    The environment is split. Our "prod" is almost brand new and uses an NVMe vSAN. As long as that environment is quick and running, very little care is given to our "ops" environment. To the business's credit, they seem to acknowledge that it's old hardware and don't seem to care a ton about downtime. As an IT professional, I loathe unscheduled downtime.

    what is OPS? I always thought of OPS as PROD...

    I could understand them not caring as much about DEV...



  • @Dashrender said in To vSAN or not to vSAN?:

    what is OPS? I always thought of OPS as PROD...
    I could understand them not caring as much about DEV...

    Try as I might, I can't get them to separate ops and dev. Ops is day to day stuff like file servers and the local domain controller. Dev is included in that if you ask the wrong person. They do not consider it prod if it's required to do their jobs, they consider it operations. Prod is customer facing websites and databases needed to serve customers. "They" being the business side of the company. I would agree with you that Ops is prod.



  • Additional questions aside, it seems that no one is in favor of a vSAN given the provided details so I'm probably going to stick with DAS. I was pretty sure it was the way to go, I just love the idea of instant vMotion.



  • @Shaman06 said in To vSAN or not to vSAN?:

    Additional questions aside, it seems that no one is in favor of a vSAN given the provided details so I'm probably going to stick with DAS. I was pretty sure it was the way to go, I just love the idea of instant vMotion.

    This isn't that we aren't in favor of vSAN. It's that you aren't in a place to take advantage of it. DAS while slower, is what you have today and you can't change that. Adding vSAN on top will make things more complex and slower (because of the complexity).

    The simple answer is replace everything and use Direct Attached storage.



  • @DustinB3403 said in To vSAN or not to vSAN?:

    DAS while slower

    DAS is fast AF



  • @Obsolesce said in To vSAN or not to vSAN?:

    @DustinB3403 said in To vSAN or not to vSAN?:

    DAS while slower

    DAS is fast AF

    But still one more hop, so slower.

    In absolute terms it's on the faster side of things.

    But when compared to internal local storage, it's slower. Don't confuse absolute and relative performance.



  • @Shaman06 said in To vSAN or not to vSAN?:

    @scottalanmiller said in To vSAN or not to vSAN?:

    What's making them want to keep running on it and investing your expensive time into supporting very cheap old gear (cheap now that it is old.)

    The environment is split. Our "prod" is almost brand new and uses an NVMe vSAN. As long as that environment is quick and running, very little care is given to our "ops" environment. To the business's credit, they seem to acknowledge that it's old hardware and don't seem to care a ton about downtime. As an IT professional, I loathe unscheduled downtime.

    If the business doesn't care, then it doesn't matter. As an IT pro, your desires should exactly mimic the business's. Any deviation in IT desiring something different than the business is a mistake on IT's side. If downtime isn't important, it isn't important, period. Don't let IT become emotional, that's common and leads to an unhealthy mismatch. IT has no needs outside of the business needs, they conceptually don't exist.



  • @Dashrender said in To vSAN or not to vSAN?:

    what is OPS? I always thought of OPS as PROD...

    Same here, prod is just the new name for ops. Ops has been production time in memorial.



  • @Shaman06 said in To vSAN or not to vSAN?:

    Try as I might, I can't get them to separate ops and dev. Ops is day to day stuff like file servers and the local domain controller.

    That's ops for sure, aka production.



  • @Shaman06 said in To vSAN or not to vSAN?:

    Additional questions aside, it seems that no one is in favor of a vSAN given the provided details so I'm probably going to stick with DAS. I was pretty sure it was the way to go, I just love the idea of instant vMotion.

    Yeah, that's the way to go here. Don't overcomplicate things, lots of effort without any real need.



  • @DustinB3403 said in To vSAN or not to vSAN?:

    @Shaman06 said in To vSAN or not to vSAN?:

    Additional questions aside, it seems that no one is in favor of a vSAN given the provided details so I'm probably going to stick with DAS. I was pretty sure it was the way to go, I just love the idea of instant vMotion.

    This isn't that we aren't in favor of vSAN. It's that you aren't in a place to take advantage of it. DAS while slower, is what you have today and you can't change that. Adding vSAN on top will make things more complex and slower (because of the complexity).

    The simple answer is replace everything and use Direct Attached storage.

    DAS is faster than vSAN. Slower than local. vSAN requires replication that introduces latency.



  • @scottalanmiller said in To vSAN or not to vSAN?:

    @Obsolesce said in To vSAN or not to vSAN?:

    @DustinB3403 said in To vSAN or not to vSAN?:

    DAS while slower

    DAS is fast AF

    But when compared to internal local storage, it's slower. Don't confuse absolute and relative performance.

    No confusion here. I was staying within context of the vSAN and DAS or vSAN using DAS scope within the post (Dustin mentioning DAS is slower than vSAN). Nobody else mentioned local storage. I'm guessing you got confused over things not said (or said by you), and thought you needed to add in some random facts about it in ways that aren't even really a factor in the case here.

    Also, it seems apparent that in the OP's case, the throughput difference between local storage and DAS is negligible. So much so as not even a consideration. There wasn't any mention of any factors to assume otherwise.



  • @scottalanmiller said in To vSAN or not to vSAN?:

    @Obsolesce said in To vSAN or not to vSAN?:

    @DustinB3403 said in To vSAN or not to vSAN?:

    DAS while slower

    DAS is fast AF

    But still one more hop, so slower.

    In absolute terms it's on the faster side of things.

    But when compared to internal local storage, it's slower. Don't confuse absolute and relative performance.

    I thought DAS (direct attached storage) was the same as internal storage, it's just sitting in a box external to the server, but the Server's RAID card has a cable to the DAS chassis, which then connects to the backplanes in the DAS chassis to disk.. no different than from the RAID controller > cable > backplane in server > disk.
    Where is my misunderstanding?

    Now the cables are longer, so maybe that's where it's slower?


Log in to reply