We Don't Have the Budget to Save Money
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@g.jacobse said:
I tossed it about a time or two,.. Software RAID or hardware - Even with my lack of knowledge and hand on experience with RAIDs, I'd go hardware.. just seems safer and more reliable.
I think what a lot of people miss is that it is more reliable when humans are involved. Good software RAID (like that built into Linux or Solaris) is rock solid. But it requires more knowledge and planning than hardware RAID does, at least the good stuff. A SmartArray or a PERC is going to "just work." You don't even need a system admin. Your server tech in the server room can swap drives when he sees an amber light come on, no need to grab the system admin for such a low level hardware task.
Put software RAID in there and that same drive swap could be a disaster and the system admin has to coordinate the swap. That blind swap capability and automated rebuilds allow for a separation of duties and an abstraction from the OS that is really critical in the SMB and is handy anywhere.
Software RAID can be great. But hardware RAID has some real advantages.
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@scottalanmiller said:
@g.jacobse said:
I tossed it about a time or two,.. Software RAID or hardware - Even with my lack of knowledge and hand on experience with RAIDs, I'd go hardware.. just seems safer and more reliable.
I think what a lot of people miss is that it is more reliable when humans are involved. Good software RAID (like that built into Linux or Solaris) is rock solid. But it requires more knowledge and planning than hardware RAID does, at least the good stuff. A SmartArray or a PERC is going to "just work." You don't even need a system admin. Your server tech in the server room can swap drives when he sees an amber light come on, no need to grab the system admin for such a low level hardware task.
Put software RAID in there and that same drive swap could be a disaster and the system admin has to coordinate the swap. That blind swap capability and automated rebuilds allow for a separation of duties and an abstraction from the OS that is really critical in the SMB and is handy anywhere.
Software RAID can be great. But hardware RAID has some real advantages.
Wouldn't hardware RAID be faster?
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@ajstringham said:
Wouldn't hardware RAID be faster?
Not since around 2001 or so. It is actually slower. There is more horsepower in the main CPUs than there is in the embedded processors even on the best RAID cards. And the best cards only have a 1GB cache whereas software RAID has as much cache as you want to throw at it, 2GB is easy, 32GB isn't unheard of.
The idea that hardware RAID is faster comes from the Pentium 32bit era (1990s) when hardware RAID was new. Back then the main CPU(s) were so slow and overloaded that offloading the parity calculations was a big deal. It was in the Pentium Pro era (inclusive of the PPro, P2, P3 and Core processors) that the CPU(s) got so fast and were so rarely overloaded that software RAID passed hardware RAID in performance. So that could have been in the 1990s but was more reasonably in the early 2000s. Big systems like Power and Sparc systems never went to hardware RAID at all (and were always the fastest systems) because they always had stable operating systems with super fast CPUs and more of them.
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@scottalanmiller said:
@ajstringham said:
Wouldn't hardware RAID be faster?
Not since around 2001 or so. It is actually slower. There is more horsepower in the main CPUs than there is in the embedded processors even on the best RAID cards. And the best cards only have a 1GB cache whereas software RAID has as much cache as you want to throw at it, 2GB is easy, 32GB isn't unheard of.
The idea that hardware RAID is faster comes from the Pentium 32bit era (1990s) when hardware RAID was new. Back then the main CPU(s) were so slow and overloaded that offloading the parity calculations was a big deal. It was in the Pentium Pro era (inclusive of the PPro, P2, P3 and Core processors) that the CPU(s) got so fast and were so rarely overloaded that software RAID passed hardware RAID in performance. So that could have been in the 1990s but was more reasonably in the early 2000s. Big systems like Power and Sparc systems never went to hardware RAID at all (and were always the fastest systems) because they always had stable operating systems with super fast CPUs and more of them.
Interesting. Good to know.
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Hardware RAID is really about improving the human interaction today more than anything. Way easier for people to understand, easier to move between devices, easier to deal with when problems arise and it can rebuild even if the OS is offline.
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@scottalanmiller said:
Hardware RAID is really about improving the human interaction today more than anything. Way easier for people to understand, easier to move between devices, easier to deal with when problems arise and it can rebuild even if the OS is offline.
Got it.
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The problem with software RAID is the raid then become tied to the OS so you need to back up the OS to get it back. Of course you can rebulid them with tools but it's not something Joe Brown is going to do. This can also become a problem with DATA software RAIDs and new OS etc. It can be done, espcially in linux but it takes some use of the command line and people would just rather have it work.
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@thecreativeone91 said:
The problem with software RAID is the raid then become tied to the OS so you need to back up the OS to get it back. Of course you can rebulid them with tools but it's not something Joe Brown is going to do. This can also become a problem with DATA software RAIDs and new OS etc. It can be done, espcially in linux but it takes some use of the command line and people would just rather have it work.
Exactly. There is nothing technically keeping you from your data but junior admins (or people who don't know the OS inside and out) might be really wary of trying to recover data from software RAID.
On the flip side, you can get at your data without the specific hardware. But with hardware RAID you need a compatible replacement card to get back at your data.
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@scottalanmiller How would you do software RAID with something like ESXi?
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Or is that even possible?
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Would you just create virtual drives from each drive on each datastore and create the software RAID at the VM level?
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@ajstringham said:
@scottalanmiller How would you do software RAID with something like ESXi?
ESXi does not support software RAID and has none built it. Hardware RAID is the only enterprise way to do that with ESXi. ESXi does support some software RAID from the likes of HP and Dell but I would never go that route.
ESXi is the only enterprise hypervisor without built-in software RAID. HyperV uses Windows software RAID, though, which is not good.
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@scottalanmiller said:
@ajstringham said:
@scottalanmiller How would you do software RAID with something like ESXi?
ESXi does not support software RAID and has none built it. Hardware RAID is the only enterprise way to do that with ESXi. ESXi does support some software RAID from the likes of HP and Dell but I would never go that route.
ESXi is the only enterprise hypervisor without built-in software RAID. HyperV uses Windows software RAID, though, which is not good.
Ok, I was wondering how that would possibly work. That makes sense.
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@ajstringham said:
Would you just create virtual drives from each drive on each datastore and create the software RAID at the VM level?
No, you would never do this. RAID goes at the bottom of the stack, not high in the stack. You would be creating an abstraction that would almost certainly look like RAID to the OS but would be a single drive underneath leaving you in horrible shape. You could make this "work" but it would be slow, fragile and messy.
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@scottalanmiller said:
@ajstringham said:
Would you just create virtual drives from each drive on each datastore and create the software RAID at the VM level?
No, you would never do this. RAID goes at the bottom of the stack, not high in the stack. You would be creating an abstraction that would almost certainly look like RAID to the OS but would be a single drive underneath leaving you in horrible shape. You could make this "work" but it would be slow, fragile and messy.
Which is what I figured, but it was the only way I could think it was possible on ESXi that I knew of.
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I have seen a lot of people, especially in labs, looking for VMware vSphere software RAID. I think that they should offer it as it is asked for so often. But I do not see it happening. That would cost a lot of money and shift more risk into VMware's lap for effectively no gain. Requiring people to buy a good, enterprise RAID card and shifting the responsibility and liability of supporting that off to the hardware vendors ultimately makes more sense. And it does not sit all that effectively with their VSAN strategy.
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@scottalanmiller said:
@ajstringham said:
@scottalanmiller How would you do software RAID with something like ESXi?
ESXi does not support software RAID and has none built it. Hardware RAID is the only enterprise way to do that with ESXi. ESXi does support some software RAID from the likes of HP and Dell but I would never go that route.
ESXi is the only enterprise hypervisor without built-in software RAID. HyperV uses Windows software RAID, though, which is not good.
Possibly because ESXi is a lot more "barebones" than Hyper-V which even the baremetal hypvervisor has a lot of windows in it still. I'm guessing XenServer uses a Linux kernel unlike ESXi.
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@thecreativeone91 correct. ESXi is the "lightest" of the hypervisors. It is the only one with zero ties to any existing OS. HyperV has no OS code in it, nor does Xen, but both rely on access to a full OS in the "control VM environment" which provides them with software RAID resources in that way. KVM is different than the other three in that it is built into the Linux kernel itself. So while KVM and Xen both use Linux MD RAID to do their software RAID Xen does it through a control environment and KVM does it directly.
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I can't quite understand how companies can't see that when they have a problem and go to a vendor to solve it, 9 times out of 10 the vendor is going to give a "solution" from stuff the vendor sells. It's like wanting to buy a fuel-efficient family car and only talking to a Hummer salesman. Of course they are going to put you in a Hummer, it's all they have to offer!
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@Dominica said:
I can't quite understand how companies can't see that when they have a problem and go to a vendor to solve it, 9 times out of 10 the vendor is going to give a "solution" from stuff the vendor sells. It's like wanting to buy a fuel-efficient family car and only talking to a Hummer salesman. Of course they are going to put you in a Hummer, it's all they have to offer!
And upsell everything so \that you spend more than you need to.. I want to haul groceries,.. not quarry gravel...
