Is JBOD Considered a Type of RAID?



  • 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.


  • Service Provider

    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.


  • Service Provider

    DAS = Direct Attached Storage.


  • Service Provider

    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.


  • Service Provider

    JBOD is missing the A. It is not an array. It is loose disks.


  • Service Provider

    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.



  • @scottalanmiller said:

    DAS = Direct Attached Storage.

    That explains the cabling...


  • Service Provider

    @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.



  • 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.



  • I should add this is a Tier II I was talking to.



  • @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



  • @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.


  • Service Provider

    @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.


  • Service Provider

    @thanksaj said:

    I should add this is a Tier II I was talking to.

    AKA Very, very junior.

    This is Tier II... helpdesk?


  • Service Provider

    @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.


  • Service Provider

    @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.



  • @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.



  • @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.



  • @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.



  • @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.



  • @IRJ said:

    @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.

    Most of the software my company sells was not made by them. They bought the company that produced it, they rebranded it, and now they train people to support it. So it's almost all secondhand training.



  • @thanksaj said:

    @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.

    Like I said, things become so proprietary its not even funny. If you were to place this guy in a SMB environment, he would likely be lost



  • I was really good friends with a guy when I first started at Lockheed Martin almost 10 years ago. We went to tech school together and I helped get him the job. He was a really bright guy. He stayed at Lockheed Martin's help desk and I moved in to a new, higher position every 2-3 years.

    I met up with him recently and I can't believe how lost he was about everything. He is the best tech at the helpdesk, but all he knows is all that Lockheed Propriety software. He hasn't got a chance to practice networking, Windows Server (since 2003), or anything else that is actually useful everywhere else.



  • @IRJ said:

    I was really good friends with a guy when I first started at Lockheed Martin almost 10 years ago. We went to tech school together and I helped get him the job. He was a really bright guy. He stayed at Lockheed Martin's help desk and I moved in to a new, higher position every 2-3 years.

    I met up with him recently and I can't believe how lost he was about everything. He is the best tech at the helpdesk, but all he knows is all that Lockheed Propriety software. He hasn't got a chance to practice networking, Windows Server (since 2003), or anything else that is actually useful everywhere else.

    My EXACT fear staying where I am longer than I have to.



  • @scottalanmiller said:

    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.

    I don't think I agree with you on this Scott. DAS, from my experience IS just a shelf of drives with either one or two scsi/SAS cables to a SCSI/SAS controller that is inside the server. The controller isn't in the external drive box. Though I will say I haven't dealt with this level of tech in quite some time, so perhaps it's changed and the controller is always in the external box now, but what would you be plugging into? Something in the PCIe slot I would assume - and what would that card be if not a controller?



  • @thanksaj said:

    @IRJ said:

    I was really good friends with a guy when I first started at Lockheed Martin almost 10 years ago. We went to tech school together and I helped get him the job. He was a really bright guy. He stayed at Lockheed Martin's help desk and I moved in to a new, higher position every 2-3 years.

    I met up with him recently and I can't believe how lost he was about everything. He is the best tech at the helpdesk, but all he knows is all that Lockheed Propriety software. He hasn't got a chance to practice networking, Windows Server (since 2003), or anything else that is actually useful everywhere else.

    My EXACT fear staying where I am longer than I have to.

    i followed a similiar path as you. Best Buy, Lockheed Martin HelpDesk, and then I get my first admin position


  • Service Provider

    @Dashrender said:

    I don't think I agree with you on this Scott. DAS, from my experience IS just a shelf of drives with either one or two scsi/SAS cables to a SCSI/SAS controller that is inside the server. The controller isn't in the external drive box. Though I will say I haven't dealt with this level of tech in quite some time, so perhaps it's changed and the controller is always in the external box now, but what would you be plugging into? Something in the PCIe slot I would assume - and what would that card be if not a controller?

    It can be. That is a DAS disk shelf, then (JBOD) and not what most people expect when they are buying enteprise storage.

    Every time that people talk about DAS in a discussion like this, you can safely assume that they meant to imply that it had its own controller internal. That's why people talk about single or dual controller enclosures, no one ever talks about a no-controller enclosure.

    Remember that RAID encapsulates disks and makes them appear as... disks. So the connector for a RAID array is SAS or SATA, just like it is for a single drive. It connects to an external SAS connector on your server (or desktop.) It attaches just like any other external hard drive. To the server, there is literally no way to tell, logically or physically, when it is talking to a single disk or when it is talking to a disk array.


  • Service Provider

    @Dashrender said:

    Something in the PCIe slot I would assume - and what would that card be if not a controller?

    It's called an HBA but it is just a SAS adapter. Or a RAID controller. RAID can attach to RAID. It is the same interface in every direction so you ca stack them indefinitely.


  • Service Provider

    @IRJ said:

    I met up with him recently and I can't believe how lost he was about everything. He is the best tech at the helpdesk, but all he knows is all that Lockheed Propriety software. He hasn't taken the time on his own to practice networking, Windows Server (since 2003), or anything else that is actually useful everywhere else.

    Fixed that for you.


  • Service Provider

    I didn't learn any of this stuff being in a business that used it. Needing to learn on the job will cripple an IT career. The job might teach somethings, but in general only specific things that the company needs. A real IT education has to be found elsewhere. Same is true for most professions. They expect you to be qualified through your own actions before doing a job, not taking a job without the skills and then they will train you for another job.