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JBOD? What the heck?
- Thread starter batotman
- Start date
I
Ice Czar
Guest
there are a few drawbacks
like if you loose a disk the JBOD array its broken
data recovery on the surviving disks is likely
but its still an inaccessable broken array
that needs to be first salvaged and
then reinitialized from scratch again
and then transfer all the surviving data back to
why dont you describe what you do have and what your trying to accomplish
like if you loose a disk the JBOD array its broken
data recovery on the surviving disks is likely
but its still an inaccessable broken array
that needs to be first salvaged and
then reinitialized from scratch again
and then transfer all the surviving data back to
why dont you describe what you do have and what your trying to accomplish
I
Ice Czar
Guest
http://www.pcguide.com/ref/hdd/perf/raid/levels/jbod-c.html
If you have some disks in a system that you decide not to configure into a RAID array, what do you do with them? Traditionally, they are left to act as independent drive volumes within the system, and that's how many people in fact use two, three or more drives in a PC. In some applications, however, it is desirable to be able to use all these disks as if they were one single volume. The proper term for this is spanning; the pseudo-cutesy term for it, clearly chosen to contrast against "redundant array of inexpensive disks", is Just A Bunch Of Disks or JBOD. How frightfully clever.
JBOD isn't really RAID at all, but I discuss it here since it is sort of a "third cousin" of RAID... JBOD can be thought of as the opposite of partitioning: while partitioning chops single drives up into smaller logical volumes, JBOD combines drives into larger logical volumes. It provides no fault tolerance, nor does it provide any improvements in performance compared to the independent use of its constituent drives. (In fact, it arguably hurts performance, by making it more difficult to use the underlying drives concurrently, or to optimize different drives for different uses.)
When you look at it, JBOD doesn't really have a lot to recommend it. It still requires a controller card or software driver, which means that almost any system that can do JBOD can also do RAID 0, and RAID 0 has significant performance advantages over JBOD. Neither provide fault tolerance, so that's a wash. There are only two possible advantages of JBOD over RAID 0:
Avoiding Drive Waste: If you have a number of odd-sized drives, JBOD will let you combine them into a single unit without loss of any capacity; a 10 GB drive and 30 GB would combine to make a 40 GB JBOD volume but only a 20 GB RAID 0 array. This may be an issue for those expanding an existing system, though with drives so cheap these days it's a relatively small advantage.
Easier Disaster Recovery: If a disk in a RAID 0 volume dies, the data on every disk in the array is essentially destroyed because all the files are striped; if a drive in a JBOD set dies then it may be easier to recover the files on the other drives (but then again, it might not, depending on how the operating system manages the disks.) Considering that you should be doing regular backups regardless, and that even under JBOD recovery can be difficult, this too is a minor advantage.
!
http://sunsite.uakom.sk/sunworldonline/swol-08-1999/swol-08-raid3.html
JBOD
"One way to create a large storage subsystem is to not use RAID at all. Such systems often go by the moniker of "just a bunch of disks," or JBOD.
JBOD is the way we used to do things back in the olden days, when normal systems maintenance included loading coal into the machine hopper and adjusting the processor drive belts. To create a JBOD storage subsystem, you take a bunch of disks and attach them to your system, usually via one or more SCSI controllers. Individual drives may have some smarts, including an on-drive cache, but there is little other hardware support for your storage subsystem.
Drive management in a JBOD environment occurs at the system level. You use conventional tools to format, partition, and mount the physical drives. Users then take advantage of the file systems you've mounted. For any sort of realistic performance management, users, especially database administrators, will need to know exactly where every file system is created and mounted, so that they don't create applications that saturate one drive or SCSI controller.
For large installations, JBOD is simply not an option. If you work in a small shop on a shoestring budget, however, JBOD can help meet some of your disk storage needs. In these cases, you'll be relying on your applications and databases to provide redundancy and recovery tools, along with robust backups to help you through serious drive failures.
The one advantage of a JBOD installation is that it forces you to become intimately familiar with your drives, controllers, and disk performance. Once you have fully grasped the inner workings of disk storage, a later transition to a more sophisticated RAID subsystem will be much easier, since you will understand how to balance loads across mmultiple controllers, detect disk hot spots, and recognize application usage patterns among your disk drives. In addition, a JBOD architecture is the basis on which software RAID solutions are constructed. Learning how to make JBOD work effectively will help you make a software-based RAID configuration work better as well. "
Dynamic Disks (Software RAID & JBOD)
Description of Disk Groups in Windows Disk Management
Dynamic vs. Basic Storage in Windows 2000
Basic and Dynamic Disks @ Windows & .net Magazine
HOW TO: Recover an Accidentally Deleted NTFS or FAT32 Dynamic Volume
Dynamic Disk Hardware Limitations (No firewire, USB, removable or laptop)
HOW TO: Set Up Fault-Tolerant Sets on Dynamic Disks in Windows 2000
Dynamic Disk Numbering and the DmDiag.exe Tool
HOW TO: Regenerate a Dynamic Mirrored Volume in Windows 2000
Restrictions on Extending or Spanning Simple Volumes on Dynamic Disks
Limits of Dynamic Disks in Windows 2000
LDMDump (Freeware utility) @ sysinternals
LDM Database @ Linux-NTFS project
LDM FAQ @ Linux-NTFS project
If you have some disks in a system that you decide not to configure into a RAID array, what do you do with them? Traditionally, they are left to act as independent drive volumes within the system, and that's how many people in fact use two, three or more drives in a PC. In some applications, however, it is desirable to be able to use all these disks as if they were one single volume. The proper term for this is spanning; the pseudo-cutesy term for it, clearly chosen to contrast against "redundant array of inexpensive disks", is Just A Bunch Of Disks or JBOD. How frightfully clever.
JBOD isn't really RAID at all, but I discuss it here since it is sort of a "third cousin" of RAID... JBOD can be thought of as the opposite of partitioning: while partitioning chops single drives up into smaller logical volumes, JBOD combines drives into larger logical volumes. It provides no fault tolerance, nor does it provide any improvements in performance compared to the independent use of its constituent drives. (In fact, it arguably hurts performance, by making it more difficult to use the underlying drives concurrently, or to optimize different drives for different uses.)
When you look at it, JBOD doesn't really have a lot to recommend it. It still requires a controller card or software driver, which means that almost any system that can do JBOD can also do RAID 0, and RAID 0 has significant performance advantages over JBOD. Neither provide fault tolerance, so that's a wash. There are only two possible advantages of JBOD over RAID 0:
Avoiding Drive Waste: If you have a number of odd-sized drives, JBOD will let you combine them into a single unit without loss of any capacity; a 10 GB drive and 30 GB would combine to make a 40 GB JBOD volume but only a 20 GB RAID 0 array. This may be an issue for those expanding an existing system, though with drives so cheap these days it's a relatively small advantage.
Easier Disaster Recovery: If a disk in a RAID 0 volume dies, the data on every disk in the array is essentially destroyed because all the files are striped; if a drive in a JBOD set dies then it may be easier to recover the files on the other drives (but then again, it might not, depending on how the operating system manages the disks.) Considering that you should be doing regular backups regardless, and that even under JBOD recovery can be difficult, this too is a minor advantage.
!
http://sunsite.uakom.sk/sunworldonline/swol-08-1999/swol-08-raid3.html
JBOD
"One way to create a large storage subsystem is to not use RAID at all. Such systems often go by the moniker of "just a bunch of disks," or JBOD.
JBOD is the way we used to do things back in the olden days, when normal systems maintenance included loading coal into the machine hopper and adjusting the processor drive belts. To create a JBOD storage subsystem, you take a bunch of disks and attach them to your system, usually via one or more SCSI controllers. Individual drives may have some smarts, including an on-drive cache, but there is little other hardware support for your storage subsystem.
Drive management in a JBOD environment occurs at the system level. You use conventional tools to format, partition, and mount the physical drives. Users then take advantage of the file systems you've mounted. For any sort of realistic performance management, users, especially database administrators, will need to know exactly where every file system is created and mounted, so that they don't create applications that saturate one drive or SCSI controller.
For large installations, JBOD is simply not an option. If you work in a small shop on a shoestring budget, however, JBOD can help meet some of your disk storage needs. In these cases, you'll be relying on your applications and databases to provide redundancy and recovery tools, along with robust backups to help you through serious drive failures.
The one advantage of a JBOD installation is that it forces you to become intimately familiar with your drives, controllers, and disk performance. Once you have fully grasped the inner workings of disk storage, a later transition to a more sophisticated RAID subsystem will be much easier, since you will understand how to balance loads across mmultiple controllers, detect disk hot spots, and recognize application usage patterns among your disk drives. In addition, a JBOD architecture is the basis on which software RAID solutions are constructed. Learning how to make JBOD work effectively will help you make a software-based RAID configuration work better as well. "
Dynamic Disks (Software RAID & JBOD)
Description of Disk Groups in Windows Disk Management
Dynamic vs. Basic Storage in Windows 2000
Basic and Dynamic Disks @ Windows & .net Magazine
HOW TO: Recover an Accidentally Deleted NTFS or FAT32 Dynamic Volume
Dynamic Disk Hardware Limitations (No firewire, USB, removable or laptop)
HOW TO: Set Up Fault-Tolerant Sets on Dynamic Disks in Windows 2000
Dynamic Disk Numbering and the DmDiag.exe Tool
HOW TO: Regenerate a Dynamic Mirrored Volume in Windows 2000
Restrictions on Extending or Spanning Simple Volumes on Dynamic Disks
Limits of Dynamic Disks in Windows 2000
LDMDump (Freeware utility) @ sysinternals
LDM Database @ Linux-NTFS project
LDM FAQ @ Linux-NTFS project
Well as my earlier post mentioned I want to stop using the RAID on my motherboard and move to a PCI solution.
My objective is to get alot space under one drive letter in order to easier categorize my things. I have many movie backups and they span greater than my 120GB hard drive so I used RAID 0 to get an essential 240GB drive.
My objective is to get alot space under one drive letter in order to easier categorize my things. I have many movie backups and they span greater than my 120GB hard drive so I used RAID 0 to get an essential 240GB drive.
I
Ice Czar
Guest
Originally posted by batotman
easier categorize
Mount a drive to an NTFS Folder
if you just want all your media to appear in a single drive, thats childs play and you dont have to sacrifice the advantages of multiple partitions (defrag\imaging\performance to position\ect)
Partitioning Strategies
In truth I think you need to consider the following
(based on both of your threads)
get a DVDR, so you can start making actual backups
switch both the 120s to single drives and throw a few partitions on each, then mount all the media they contain to a single folder
get 2 small drives that combined in a RAID 0 will handle the largest file you can possible imagine as a performance drive (OS\Swap + encoded file)
Consider running a real RAID array right now your running AID, there is nothing redundant about it, with a RAID5 array you can loose a HDD and still not loose any data. You can even have it setup to automatically rebuild with a hot spare attached. RAID5 main advantage is its efficiency (If all drives are the same size, ( (Number of Drives - 1) / Number of Drives).
example
3 x 80GB = 160GB (R5)
4 x 80GB = 240GB
5 x 80GB = 320GB
6 x 80GB = 400GB
7 x 80GB = 480GB
8 x 80GB = 560GB
9 x 80GB = 640GB
ect
the greater the number of drives the greater the efficiency
there are IDE controllers with up to 12 channels (one drive per channel)
you could also review those Dynamic Disk Links, but software RAID leaves alot to be desired