Should We Ever Talk About JBODs
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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.
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I've always taken JBOD to mean disks concatenated together and presented as 1 disk to the OS
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@brianlittlejohn said in Should We Ever Talk About JBODs:
I've always taken JBOD to mean disks concatenated together and presented as 1 disk to the OS
So the opposite of the term
Instead of being separate disks, you feel that they are explicitly not separate?This highlights that not only do I feel that the term is redundant, it is also simply unknown. Everyone has a different definition, but all of them overlap with existing, explicit terms.
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If we go by Wikipedia...
https://en.wikipedia.org/wiki/Non-RAID_drive_architectures
JBOD is specifically a reference to non-RAID and non-span. So both the examples presented thus far (SS and concat/spans) are what JBOD, in theory according to wikipedia, should be telling us that we don't have. SS would be a RAID form, spanning is... well spanning.
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This is the wikipedia definition: "JBOD (derived from "just a bunch of disks"): described multiple hard disk drives operated as individual independent hard disk drives."
Basically, anything that ties the disk together (RAID, RAIN, Spans, etc.) would be the antithesis. All non-JBOD systems must, obviously, use JBOD under the hood, there is no way not to. But that's what we just call the disks.
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@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?
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@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.
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@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.
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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.
