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About Partitions, Volumes and Drives
- Thread starter doubledee
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Looks like I'm coming up with lots of questions while reading the CCC Manual!!
Can someone please explain what the difference is between a "Partition", a "Volume" and a "Drive"?
Thanks,
Debbie
A drive is a physical drive. It can be formatted into one or more partitions, which are also referred to as volumes when you are mounting them.
Back in my Windows days, here are the terms I used... (Pretty industry standard)
Physical Drive ---> Physical Storage Device (e.g. Internal/External HDD)
Logical Drive ---> Logical Division of Physical Drive (e.g. C: , D: , E: )
Partition ---> Same as "Logical Drive" (e.g. C: , D: , E: )
If you so desired, you could "partition" your "Physical" HDD into several "Logical" Drives (or "Partitions") to segment your Apps and Data.
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So, to translate from that terminology in the PC world, to the Mac world, here is how I think it would go...
Code:
Logical Drive (PC) = Partition (PC, Mac) = Volume (Mac)Does that sound correct?
Debbie
There is not necessarily a 1:1 correspondence between a Volume and a Partition.
RAID lets you combine several disks together in such a manner that information is replicated across physical drives. This provides some protection against failures which in a single-drive-Volume relationship could cause data to become unavailable. It is not a backup solution, and its geared towards keeping information online.
CoreStorage allows you to define Logical Volume Groups which can span multiple partitions on multiple devices, presenting them as a single entity as a Logical Volume. This is how Apple's Fusion Drive combines a solid-state and standard platter disk together into what appears to be a single disk. Where the information is physically stored is up to the CoreStorage engines.
In both of these cases, what appears to the user is a single Volume which you can browse in the Finder. That single volume could be backed by many different physical disks and/or partitions; logically they are treated as a single entity.
RAID lets you combine several disks together in such a manner that information is replicated across physical drives. This provides some protection against failures which in a single-drive-Volume relationship could cause data to become unavailable. It is not a backup solution, and its geared towards keeping information online.
CoreStorage allows you to define Logical Volume Groups which can span multiple partitions on multiple devices, presenting them as a single entity as a Logical Volume. This is how Apple's Fusion Drive combines a solid-state and standard platter disk together into what appears to be a single disk. Where the information is physically stored is up to the CoreStorage engines.
In both of these cases, what appears to the user is a single Volume which you can browse in the Finder. That single volume could be backed by many different physical disks and/or partitions; logically they are treated as a single entity.
I'm going to go out on a limb and take a wild guess that given the OP's original question, a RAID array is not involved.
ElectricSheep makes a valid point, but you are correct, GGJstudios, in that I am not dealing with RAID!
To make my response above more accurate, I should have said, "For a laptop/computer with a single drive, I guess that a Logical Drive = Partition = Volume"
There!
Debbie
While you may not be dealing with RAID, you may still run into CoreStorage where Volumes are not necessarily the same as Partitions, if for example you are using FileVault2. Although at-least in that case it won't be spanned over multiple disks.