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f0rbez

Partitions: Primary vs Logical?

11 posts in this topic

I'm curious which would be safer for data. I plan on using it entirely for data (mp3s, movies).

The partition magic tutorial said that generally logical should be used for data storage, and primary should be used for OS's. This is due to the fact that most OS's can't have more than one visible primary partition.

Regardless though, I'd like to use whatever is going to be safer for my stuff.

I thought that using logical may prevent things from happening to that drive. For example, an OS or programs attempting to modify the partition.

Any thoughts?

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how are you/what software are you using, to partition the hard drive?

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Playing with partition magic right now. Its my first time using it.

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Hi there,

I've used PartitionMagic in the past. It's a good solid partitioning program.

I don't think that you should have to worry about logical vs primary that much. If you're running anything non-Win9x, then just go for all primary drives. That's the way I've had my computers set up for a long time and it's all good.

Another thing to realize is that logical drives are actually placed on one extened partition (i.e. a partition within a parition). If that extended partition screws up on you, then you loose all the paritions within it. (I've had this happen once... it sucked)

You said that you were worried about the OS that can access the hard drive. The only OS that you need to worry about is the one that you are running. Any computers that you share with will just call for the files through your OS.

Hope this helps.

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Another thing to realize is that logical drives are actually placed on one extened partition (i.e. a partition within a parition). If that extended partition screws up on you, then you loose all the paritions within it. (I've had this happen once... it sucked)

eek, well i definately wouldn't want something like that to happen. I guess that complicating the partition setup like that would make it more unreliable.

Basically, I should go with a primary partition for the data, unless I'm using one of the older windows operating systems?

Do other operating systems besides older windows have problems with multiple primaries?

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I think that you should look into those other OSes for information on partitions and such. I would imagine that any current distro of Linux would support multiple primary partitions.

Have a look around for information on your OS. AFAIK, you should be fine with multiple primary partitions. I can't really see why it would cause any problems.

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Actually, from a purely statistical point of view, logical partitions (logical volumes inside Extended partition) are safer.

In the MBR (Master Boot Record) of each DRIVE there is space for just FOUR partition ENTRIES.

Of those entries, only one can be relative to an Extended LOGICAL VOLUME.

The other 3 entries can be primary.

A few Operating Systems, including DOS, complained about multiple Primary Partitions FORMATTED WITH A KNOWN FILESYSTEM.

It is perfectly safe to have a partition table like this:

1) Primary Active FAT16 (with DOS)

2) Primary NTFS (dos cannot read it)

3) Primary FAT32 (dos cannot read it)

4) Extended

As said before, the entry for the Extended one does not point to an actual partition, but to a LOGICAL CONTAINER, inside which you can make as many logical partitions you need.

To make it more clear, the difference in the entries is this:

1) the entry relative to Primary partition is the actual start address of the partition

2) the entry relative to Extended partition is the start address of the logical container; at the said address are stored the start addresses of the logical partitions within the Extended partition

So the actual partition tables of logical partitions are NOT stored on track 0 of the HD.

If you get a "dumb" virus, it will probably try to wipe the first "n" sectors of your HD, you will lose info on WHERE the logical volume starts, but NOT the info on the LOGICAL PARTITIONS.

There are tens of freeware tools that can let you find the info that was wiped, whilst finding the actual partition info is a bit more difficult.

The same thing applies if you make a mistake editing directly the MBR.

And even from a statistical point of view, track 0 of the HD has numberless more accesses in a HD lifetime that track "nn" (where logical volume starts) so it is highly probable that a misreading can happen more likely on track 0 that on any other track.

I hope that the above is clear enough, sometimes trying to explain things I make it worse.

jaclaz

Edited by jaclaz
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So given my situation: I want to format the entire drive as one partition and store only data with no operating systems or programs running from it.

Would I want to partition that entire drive as an extended partition and then create another logical partition inside (also taking up the entire extended partition)?

You said that a virus could wipe the first track 0 which would not harm the data but would kind of "hide" the partition, right? But if I was using a primary partition and track 0 was wiped, I would lose actual data instead of just the partition info?

Norton PartitionMagic seems to suggest using logical partitions for data and other uses, and primary for just operating systems. I wasn't sure the basis behind that so I figured it may be more protected.

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You said that a virus could wipe the first track 0 which would not harm the data but would kind of "hide" the partition, right?
If a virus (or whatever else) overwrites track 0 it will delete:

Master Boot Record, which contains:

1) Boot Record

2) Partition Table

In the case I was describing, the actual Partition Table of an Extended volume is NOT there, so that it cannot be wiped and it is easy to recover.

But if I was using a primary partition and track 0 was wiped, I would lose actual data instead of just the partition info?

No you would lose just the partition info.

All the discussion above applies to a drive that holds MULTIPLE PARTITIONS, if you want to make just one partition on the drive it DOES NOT matter whether it is logical or not.

Should havoc happen (Track 0 overwritten) you would just need a Partition Editor like Ranish's one:

www.ranish.com/part

and manually write a new partition table starting at Cyl 0 Side 1 Sect 1 and ending at Cyl (last Cylinder) Side (last side) Sector (last sector).

jaclaz

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...Norton PartitionMagic seems to suggest using logical partitions for data and other uses, and primary for just operating systems....

Bootable partitions MUST be primary. Non-bootable are logical.

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If you want compleet safe data storage you can beter you an other hard disk then where your os is running on.

If you want completle safe you can use a raid 0 setup, with two hard disks.

But as say already mostly OS are installed on a primary partition and if you want to have more than 4 partitions (to sepparate your data or to have less fragmentation of your hard disk) you must use logical partitions in an extentend partion.

Good luck

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