Is JBOD Considered a Type of RAID?
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Was talking to a co-worker earlier, who was talking about one of the products that my company sells, which is a DAS (I believe it's Distributed Array of Storage but aren't 100% on that). Basically, it's a device that acts like a SAN, I think. It can have anywhere from 10-100TB of storage. This brings me to my question.
The drives used on the DAS are JBOD (Just a Bunch Of Disks/Drives). Now, he said JBOD is a form of RAID. I know that they are often talked in conjunction, but to me there is RAID, which is primarily 0, 1, 5, 6, or 10 when discussed. JBOD is just each stand-alone, therefore it's missing the R in RAID. It's not redundant. JBOD is the opposite of RAID. Like I said, they are often talked about together, but JBOD is not a form of RAID, as far as I'm concerned.
Am I wrong? I just want to know more for my own reference.
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No, in no way whatsoever. The term JBOD is a colloquial term that simply means "not RAID." It's only purpose is to designate something as not being RAID at all. So the opposite of RAID.
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DAS = Direct Attached Storage.
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A DAS and a SAN are two ways to hook up a disk array. A disk array that is attached directly to a computer is a DAS, that same disk array if first attached to a switch, is a SAN. DAS and SAN are use cases, not things.
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JBOD is missing the A. It is not an array. It is loose disks.
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What you are selling is a disk shelf. It is just a shelf that holds disks, that's it. It's a dumb unit (literally, as in it contains no logic.) It is metal and cables. A JBOD shelf is something you can easily construct in your garage. It's only marginally able to be called a "device" as it is just a holding container for disks, their power and their cables. You could make one of these with a bunch of USB cables hanging out of the back and call it the same thing. It's little different than taking a wood box and putting slots in it to hold external drives and danging the USB connectors out the back. It will work, but who would use that in a business?
When people talk about DAS and SAN, they are talking "disk arrays", not "disk shelves." This isn't a hard and fast rule, but it applies ~99% of the time. If you make a SAN out of a JBOD you have a total disaster on your hands, but it can be done. The Netgear SC101 is the most ridiculous SAN unit ever, and that is what it was. To be an array means that the disks work together (RAID) and that means that the logic, the controller, is inside the disk array. So a disk array, as everyone who says DAS or SAN means to imply, always has a controller. A JBOD shelf lacks that controller.
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@thanksaj said:
@scottalanmiller said:
DAS = Direct Attached Storage.
That explains the cabling...
You can think of a SAN as being IAS, Indirect Attached Storage. The term DAS is a reference to the storage itself - it is plugged right in. The term SAN is a reference to the entire network on which the storage exists, so the two terms while competing ideas are not exactly opposites of each other. The SAN includes the disk arrays, monitoring, switches, HBAs, etc. But people normally use the term to simple refer to the disk arrays on the SAN that are attached to switches of some type.
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Ok, but to confirm my answer, JBOD is NOT a type of RAID. Which is what I wanted to confirm, because that's what I said. I told him JBOD is anti-RAID.
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I should add this is a Tier II I was talking to.
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@thanksaj said:
I should add this is a Tier II I was talking to.
Tier II in a corporate environment doesn't really mean much. They don't get to touch alot of equipment and are usually somewhat of a horse with blinders on
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@IRJ said:
@thanksaj said:
I should add this is a Tier II I was talking to.
Tier II in a corporate environment doesn't really mean much. They don't get to touch alot of equipment and are usually somewhat of a horse with blinders on
Same tech was using the terms incremental and differential interchangeably, in terms of backups.
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@thanksaj said:
Ok, but to confirm my answer, JBOD is NOT a type of RAID. Which is what I wanted to confirm, because that's what I said. I told him JBOD is anti-RAID.
It's not anti-RAID, it doesn't block RAID at another level or anything like that. It is simply the term that exists to denote when a group of disks exist but are not RAID. The term only exists as an opposite to RAID.
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@thanksaj said:
I should add this is a Tier II I was talking to.
AKA Very, very junior.
This is Tier II... helpdesk?
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@thanksaj said:
Same tech was using the terms incremental and differential interchangeably, in terms of backups.
Yeah, sounds like Tier II is likely a post intern, but very junior position. Those are very basic terms.
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@IRJ said:
Tier II in a corporate environment doesn't really mean much. They don't get to touch alot of equipment and are usually somewhat of a horse with blinders on
Tiers in general mean nothing. I never saw any environment use them until I saw SMB communities talk about them. It is some weird thing that happens when small business isolated IT people try to extrapolate what they imagine enterprise IT must be like and this weirdness results.
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@scottalanmiller said:
@thanksaj said:
Ok, but to confirm my answer, JBOD is NOT a type of RAID. Which is what I wanted to confirm, because that's what I said. I told him JBOD is anti-RAID.
It's not anti-RAID, it doesn't block RAID at another level or anything like that. It is simply the term that exists to denote when a group of disks exist but are not RAID. The term only exists as an opposite to RAID.
Ok, I was using anti as opposite. My bad.
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@scottalanmiller said:
@thanksaj said:
I should add this is a Tier II I was talking to.
AKA Very, very junior.
This is Tier II... helpdesk?
He's at least 10 years older than me.
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@scottalanmiller said:
@IRJ said:
Tier II in a corporate environment doesn't really mean much. They don't get to touch alot of equipment and are usually somewhat of a horse with blinders on
Tiers in general mean nothing. I never saw any environment use them until I saw SMB communities talk about them. It is some weird thing that happens when small business isolated IT people try to extrapolate what they imagine enterprise IT must be like and this weirdness results.
I worked corporate (Lockheed Martin) IT Helpdesk and later Tier 2 priority management. Even the term management meant basically nothing. I just managed assigning tickets to other Teir 2 techs.
Low level corporate IT is tough. You tend to do things in a way that is so proprietary its not even funny. Yet you know nothing about the actual infrastructure. Almost all software is made in house or at least heavily modified.
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@scottalanmiller said:
@thanksaj said:
Same tech was using the terms incremental and differential interchangeably, in terms of backups.
Yeah, sounds like Tier II is likely a post intern, but very junior position. Those are very basic terms.
He's one of the best we have on this product for Tier II. I was just surprised at the blatant ignorance on the basic term. Basically, that's what I don't want to become working proprietary software support. You get good at one or two products, but start losing your general IT grasps.
