Should We Ever Talk About JBODs
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@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
What conversation are you picturing where using the term disks or using the term JBOD would separate things? Every RAID array is JBOD under the hood. So any situation where saying disks would be confusing, so would JBOD.
In fact, the conversation that triggered this was someone using exactly these wrong terms - calling the banks of his RAID 10 disks JBODs when looking "under" the RAID level. And he's as much right as not, they are indeed JBOD at that level. But he could have just said "disks", too.
I meant it as that disks can be either raided or unraided. JBODs cannot be raided. If they were raided, it wouldn't be a JBOD anymore. However, a disk can still be a disk whether it's raided or not. See what I mean?
Kind of. But when you look under a RAID array, it's a JBOD still... because under that level they are not yet RAIDed.
The SS world uses JBOD in that way.... it's JBOD even though RAID is on top.
Ah you replied before I could clarify, but you raised a good point.
Maybe JBOD is best described as what's presented to the OS? Maybe that's a direction we could take this?
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@Tim_G said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
What conversation are you picturing where using the term disks or using the term JBOD would separate things? Every RAID array is JBOD under the hood. So any situation where saying disks would be confusing, so would JBOD.
In fact, the conversation that triggered this was someone using exactly these wrong terms - calling the banks of his RAID 10 disks JBODs when looking "under" the RAID level. And he's as much right as not, they are indeed JBOD at that level. But he could have just said "disks", too.
I meant it as that disks can be either raided or unraided. JBODs cannot be raided. If they were raided, it wouldn't be a JBOD anymore. However, a disk can still be a disk whether it's raided or not. See what I mean?
I still feel I need to clarify what I mean, as it can be taken differently than how I mean it.
If you have a RAID, it consists of disks. Those disks are still called disks whether they are in a raid or not. However, if you have a JBOD, you can be certain that there is no RAID involved because it's still at the JBOD stage. Once you apply RAID to a JBOD, it's no longer a JBOD then.
I understand what you mean. At least I think that I do. But let's break it down architecturally.
The storage team could provide tons of disks to the server team. To the storage teams it's always JBOD. But to the server team it might be RAID or a span. It's still JBOD, and still RAID. Depends where you are looking.
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@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
What conversation are you picturing where using the term disks or using the term JBOD would separate things? Every RAID array is JBOD under the hood. So any situation where saying disks would be confusing, so would JBOD.
In fact, the conversation that triggered this was someone using exactly these wrong terms - calling the banks of his RAID 10 disks JBODs when looking "under" the RAID level. And he's as much right as not, they are indeed JBOD at that level. But he could have just said "disks", too.
I meant it as that disks can be either raided or unraided. JBODs cannot be raided. If they were raided, it wouldn't be a JBOD anymore. However, a disk can still be a disk whether it's raided or not. See what I mean?
Kind of. But when you look under a RAID array, it's a JBOD still... because under that level they are not yet RAIDed.
The SS world uses JBOD in that way.... it's JBOD even though RAID is on top.
Ah you replied before I could clarify, but you raised a good point.
Maybe JBOD is best described as what's presented to the OS? Maybe that's a direction we could take this?
That's problematic too. Because software RAID is after the OS, but before the file system. Would a Synology be a JBOD?
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@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
What conversation are you picturing where using the term disks or using the term JBOD would separate things? Every RAID array is JBOD under the hood. So any situation where saying disks would be confusing, so would JBOD.
In fact, the conversation that triggered this was someone using exactly these wrong terms - calling the banks of his RAID 10 disks JBODs when looking "under" the RAID level. And he's as much right as not, they are indeed JBOD at that level. But he could have just said "disks", too.
I meant it as that disks can be either raided or unraided. JBODs cannot be raided. If they were raided, it wouldn't be a JBOD anymore. However, a disk can still be a disk whether it's raided or not. See what I mean?
Kind of. But when you look under a RAID array, it's a JBOD still... because under that level they are not yet RAIDed.
The SS world uses JBOD in that way.... it's JBOD even though RAID is on top.
Ah you replied before I could clarify, but you raised a good point.
Maybe JBOD is best described as what's presented to the OS? Maybe that's a direction we could take this?
That's problematic too. Because software RAID is after the OS, but before the file system. Would a Synology be a JBOD?
Depends on how you look at it. A JBOD (of many disks) is presented to the OS as a bunch of single disks. A RAID (of many disks) is presented to OS as a single disk.
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@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
What conversation are you picturing where using the term disks or using the term JBOD would separate things? Every RAID array is JBOD under the hood. So any situation where saying disks would be confusing, so would JBOD.
In fact, the conversation that triggered this was someone using exactly these wrong terms - calling the banks of his RAID 10 disks JBODs when looking "under" the RAID level. And he's as much right as not, they are indeed JBOD at that level. But he could have just said "disks", too.
I meant it as that disks can be either raided or unraided. JBODs cannot be raided. If they were raided, it wouldn't be a JBOD anymore. However, a disk can still be a disk whether it's raided or not. See what I mean?
Kind of. But when you look under a RAID array, it's a JBOD still... because under that level they are not yet RAIDed.
The SS world uses JBOD in that way.... it's JBOD even though RAID is on top.
Ah you replied before I could clarify, but you raised a good point.
Maybe JBOD is best described as what's presented to the OS? Maybe that's a direction we could take this?
That's problematic too. Because software RAID is after the OS, but before the file system. Would a Synology be a JBOD?
Depends on how you look at it. A JBOD (of many disks) is presented to the OS as a bunch of single disks. A RAID (of many disks) is presented to OS as a single disk.
Not most RAID. Only hardware RAID.
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Maybe a disk is to a RAID as a brick is to a house. A JBOD is to a RAID as a truck of bricks are to a house.
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@Tim_G said in Should We Ever Talk About JBODs:
Maybe a disk is to a RAID as a brick is to a house. A JBOD is to a RAID as a truck of bricks are to a house.
That was my original thought. And in that case we'd just call them "bricks". No need for a special term for the bricks themselves beyond that.
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@Tim_G said in Should We Ever Talk About JBODs:
Maybe a disk is to a RAID as a brick is to a house. A JBOD is to a RAID as a truck of bricks are to a house.
I say that because the word 'disk' is in JBOD. A bunch of disks. Not a single disk. A single disk can be a disk by itself... it could be a part of an existing raid, or it might not be. A JBOD is a bunch of disks. The definition of JBOD is that it's a bunch of disks, that are not yet part of a RAID, which also has the word 'disk' in it.
If you say a JBOD is the underlying foundation of a RAID... it's not. Yes, a RAID is made up of a bunch of disks. But to say you have a RAID on top of a JBOD... you are kind of saying you have a house built on top of a truck of bricks. Yes, you built it from a truck of bricks, but it's no longer a truck of bricks. Just like those disks are no longer a JBOD, now that they are RAIDED.
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@Tim_G said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
Maybe a disk is to a RAID as a brick is to a house. A JBOD is to a RAID as a truck of bricks are to a house.
I say that because the word 'disk' is in JBOD. A bunch of disks. Not a single disk. A single disk can be a disk by itself... it could be a part of an existing raid, or it might not be. A JBOD is a bunch of disks. The definition of JBOD is that it's a bunch of disks, that are not yet part of a RAID, which also has the word 'disk' in it.
If you say a JBOD is the underlying foundation of a RAID... it's not. Yes, a RAID is made up of a bunch of disks. But to say you have a RAID on top of a JBOD... you are kind of saying you have a house built on top of a truck of bricks. Yes, you built it from a truck of bricks, but it's no longer a truck of bricks. Just like those disks are no longer a JBOD, now that they are RAIDED.
So in that case SS cannot use JBOD nor can RAID. Everything starts as JBOD and nothing ends as it. So never a time to use the term, right?
And JBOD is something you can never know about at the storage layer if you are using this definition. Even if you make JBOD and present JBOD to the next team or layer, their use of it would make it no longer JBOD.
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@Tim_G said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
Maybe a disk is to a RAID as a brick is to a house. A JBOD is to a RAID as a truck of bricks are to a house.
I say that because the word 'disk' is in JBOD. A bunch of disks. Not a single disk. A single disk can be a disk by itself... it could be a part of an existing raid, or it might not be. A JBOD is a bunch of disks. The definition of JBOD is that it's a bunch of disks, that are not yet part of a RAID, which also has the word 'disk' in it.
If you say a JBOD is the underlying foundation of a RAID... it's not. Yes, a RAID is made up of a bunch of disks. But to say you have a RAID on top of a JBOD... you are kind of saying you have a house built on top of a truck of bricks. Yes, you built it from a truck of bricks, but it's no longer a truck of bricks. Just like those disks are no longer a JBOD, now that they are RAIDED.
Not a "truck" of bricks. Just "bricks". JBOD implies nothing more than plural, two. You absolutely say a house is built if bricks. So you say RAID is built of JBOD.
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"Truck of" isn't analogous because it specifies rough quantity as well as the truck as a container. JBOD has no specific quantity nor container.
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@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
Maybe a disk is to a RAID as a brick is to a house. A JBOD is to a RAID as a truck of bricks are to a house.
I say that because the word 'disk' is in JBOD. A bunch of disks. Not a single disk. A single disk can be a disk by itself... it could be a part of an existing raid, or it might not be. A JBOD is a bunch of disks. The definition of JBOD is that it's a bunch of disks, that are not yet part of a RAID, which also has the word 'disk' in it.
If you say a JBOD is the underlying foundation of a RAID... it's not. Yes, a RAID is made up of a bunch of disks. But to say you have a RAID on top of a JBOD... you are kind of saying you have a house built on top of a truck of bricks. Yes, you built it from a truck of bricks, but it's no longer a truck of bricks. Just like those disks are no longer a JBOD, now that they are RAIDED.
So in that case SS cannot use JBOD nor can RAID. Everything starts as JBOD and nothing ends as it. So never a time to use the term, right?
And JBOD is something you can never know about at the storage layer if you are using this definition. Even if you make JBOD and present JBOD to the next team or layer, their use of it would make it no longer JBOD.
SS requires JBOD. RAID requires JBOD, too.
I think JBOD term itself in the industry has been formed to mean an enclosure of a bunch of disks... such as a DAS enclosure you'd hook up to a server via an HBA.
Perhaps that's not technically correct, but for practical purposes, it works.
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@scottalanmiller said in Should We Ever Talk About JBODs:
@DustinB3403 said in Should We Ever Talk About JBODs:
As a term JBOD doesn't make a lot of sense, I agree. The term I think was meant more as marketing then a technical term.
I've literally never heard any vendor use the term in marketing, white papers, in person... nothing. I've never heard the term outside of SMB IT pros talking about... random things.
Hold the phone.. didn't MS use it for a bit while talking about Exchange?
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@Dashrender said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
@DustinB3403 said in Should We Ever Talk About JBODs:
As a term JBOD doesn't make a lot of sense, I agree. The term I think was meant more as marketing then a technical term.
I've literally never heard any vendor use the term in marketing, white papers, in person... nothing. I've never heard the term outside of SMB IT pros talking about... random things.
Hold the phone.. didn't MS use it for a bit while talking about Exchange?
Really?
I've seen it used all over the place in official docs. Just a super quick search as an example: https://technet.microsoft.com/en-us/library/hh831739(v=ws.11).aspx
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@Tim_G said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
@Tim_G said in Should We Ever Talk About JBODs:
Maybe a disk is to a RAID as a brick is to a house. A JBOD is to a RAID as a truck of bricks are to a house.
I say that because the word 'disk' is in JBOD. A bunch of disks. Not a single disk. A single disk can be a disk by itself... it could be a part of an existing raid, or it might not be. A JBOD is a bunch of disks. The definition of JBOD is that it's a bunch of disks, that are not yet part of a RAID, which also has the word 'disk' in it.
If you say a JBOD is the underlying foundation of a RAID... it's not. Yes, a RAID is made up of a bunch of disks. But to say you have a RAID on top of a JBOD... you are kind of saying you have a house built on top of a truck of bricks. Yes, you built it from a truck of bricks, but it's no longer a truck of bricks. Just like those disks are no longer a JBOD, now that they are RAIDED.
So in that case SS cannot use JBOD nor can RAID. Everything starts as JBOD and nothing ends as it. So never a time to use the term, right?
And JBOD is something you can never know about at the storage layer if you are using this definition. Even if you make JBOD and present JBOD to the next team or layer, their use of it would make it no longer JBOD.
SS requires JBOD. RAID requires JBOD, too.
I think JBOD term itself in the industry has been formed to mean an enclosure of a bunch of disks... such as a DAS enclosure you'd hook up to a server via an HBA.
Perhaps that's not technically correct, but for practical purposes, it works.
Yeah, everything requires JBOD, then it stops being JBOD
Hence the problem. It's all JBOD at some level or early on. And it's all not JBOD later. -
@Tim_G said in Should We Ever Talk About JBODs:
@Dashrender said in Should We Ever Talk About JBODs:
@scottalanmiller said in Should We Ever Talk About JBODs:
@DustinB3403 said in Should We Ever Talk About JBODs:
As a term JBOD doesn't make a lot of sense, I agree. The term I think was meant more as marketing then a technical term.
I've literally never heard any vendor use the term in marketing, white papers, in person... nothing. I've never heard the term outside of SMB IT pros talking about... random things.
Hold the phone.. didn't MS use it for a bit while talking about Exchange?
Really?
I've seen it used all over the place in official docs. Just a super quick search as an example: https://technet.microsoft.com/en-us/library/hh831739(v=ws.11).aspx
And look, it's used incorrectly. What does it even mean in Microsoft's world? They say "disks and JBODs" as if they are two different things. If a JBOD is not "just a bunch of disks" then Microsoft has made up a new meaning of the term. Where do they define it?
Maybe they mean "enclosure of disks" but then we can't say that anything requires a JBOD because by definition, nothing would know when it does or does not have one.
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Apparenty, JBODs in Microsoft's world are way, way more than we are normally thinking: "JBOD storage enclosures are designed with redundant hardware—such as JBOD controllers, SAS ports, and power supplies—to avoid a single point of failure if a part goes down."
So according to MS, only highly redundant enclosures are JBODs. So a totally new misuse of the term that's unique to them. And what is a "JBOD controller", another new term.
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I tend t agree with you Scott - JBOD has never really made sense to me. It has no safety or recoverability, so what's the point.
When I read about Exchange using it, I basically saw MS using it like Drobo with their Beyond RAID stuff, only MS was handling it transparently behind Exchange. Though I never real dug into it that much.
Though now I don't know that they actually applied any RAID type magic to the JBOD and instead relied upon DAG for their recoverability.
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@Dashrender said in Should We Ever Talk About JBODs:
I tend t agree with you Scott - JBOD has never really made sense to me. It has no safety or recoverability, so what's the point.
When I read about Exchange using it, I basically saw MS using it like Drobo with their Beyond RAID stuff, only MS was handling it transparently behind Exchange. Though I never real dug into it that much.
Though now I don't know that they actually applied any RAID type magic to the JBOD and instead relied upon DAG for their recoverability.
They use data protection, it's just higher in the stack. It's not RAID, but the equivalent is there. Same with SQL Server. They are never recommending that you use JBOD for any of those, not actual JBOD. MS is just using the term in a totally unique and made up way that doesn't match anyone else's definition and no one is, I don't think, 100% sure how MS is using it.
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This is what Microsoft considers a JBOD: https://www.windowsservercatalog.com/results.aspx?&bCatID=1645&cpID=0&avc=10&ava=0&avt=0&avq=0&OR=1&PGS=25
An enclosure of a bunch of disks: "...just-a-bunch-of-disks (JBOD) enclosure" as in the above link that they point to.
So a JBOD, is a specific object or product. Yes, the words themselves have a different meaning than when used as a whole.
For example, this is a JBOD: http://dataonstorage.com/dns-jbod-enclosure/dns-2608-4u-32-bay-12gbps-sas-enterprise-jbod-storage-enclosure.html
This is NOT a JBOD:
Going word-by-word, yes, the above is just a bunch of disks. For sure. That is what it is. But it's useless like that.
What a JBOD is in IT terms, is a JBOD enclosure specifically. When you refer to a JBOD, you are referring something like Microsoft links to or one of those DataON JBOD storage enclosures.
I think you are thinking too deep into it looking to pick it apart. Going in to it with the preconception of it being wrong will lead you to nitpicking.
If I were you, I would sum up the definition of what JBOD is supposed to mean. Not nitpick it apart to make it mean the literal pile of disks the individual words mean. I believe it is supposed to mean what I linked above: http://dataonstorage.com/dns-jbod-enclosure/dns-2608-4u-32-bay-12gbps-sas-enterprise-jbod-storage-enclosure.html. And I also believe that's what most IT Professionals think it means. Sure, you'll have the few who are just wrong, but the majority I'm talking about. Maybe not, but the people who deal with the things do.
