Actual required partition space required for cloning?

[sparkie7]

Quick question: I'm cloning/backing up my 250GB boot drive which has all my sys, apps and docs on it. I have a larger 320GB target drive to back up on. But I want to partition it up into 2 partitions. One for the boot clone and the other for other junk. When I go to disk utility it says the Total Capacity of my 250 is 238.1 GB. So, should I partition my target clone partition at say 240 GB (to get more out of the 2nd partition)(or is that inadequate when my source drive gets full up at a later date) or 250 GB or 256 GB (to be really safe)?

Please advise

PS I'm using Carbon Copy Cloner and want to do a block level copy

 

[MacDawg]

How much of the 250 is actually being used?
If you are only using say 130, then you don't need to partition 250
Just make it "comfortably" larger than what you are currently using

Edit: you edited your post... so I would say you probably need to make it the same size

Woof, Woof - Dawg

 

[sparkie7]

How much of the 250 is actually being used?
If you are only using say 130, then you don't need to partition 250
Just make it "comfortably" larger than what you are currently using

Edit: you edited your post... so I would say you probably need to make it the same size

Woof, Woof - Dawg

yeh, i want to use it to back up on a continual basis. and want to make sure i size the partition up properly from the start. so should i partition at 240, 250 or 256 GB?

 

[MacDawg]

Well, I use CCCloner as well, but here's my backup strategy...

I have a 1TB external that I have partitioned into 3 parts

1. About 150% the size of what is currently used on my HD... used for Time Machine. This gives me incremental backups and the ability to go back in time for any reason (deleted files, corrupt files, settings, etc.) Time Machine automatically deletes the oldest backup if it fills the drive.

2. About 150% the size of what is currently used on my HD ... used for Carbon Copy Cloner. This backs up weekly and gives me a bootable clone in case of catastrophic failure. If my usage ever exceeds the size of the drive I will repartition and clone fresh, but that is not likely.

3. The remainder of the drive... for any general storage I want to use it for

Not sure if that helps or not... but Time Machine and Cloning have 2 different approaches to backups. I want to take advantage of both.

Woof, Woof - Dawg

 

[sparkie7]

why 150%?

so say if you have a 250GB Source drive, your "allocated" back up partitions are 375GB? (150%). Whats the reasoning.. Isn't that a waste of drive space?

 

[MacDawg]

Not the actual size of the drive, the actual space being used

Let's say I have a 250 drive but I am only currently using 140
I want my backup to hold that much and more (because I will be adding to the usage)
Also, Time Machine is incremental, and will add more and more space until it fills the drive (eventually) and then will begin deleting the oldest backups. I want space to grow and still have my backups relevant.

Same with CCCloner, if I am using 140 I want my drive larger because I will be adding files and the additional files will be added to the clone.

If you have a 250 and it is full, there is no reason to make a drive larger than the actual capacity of your drive, because it will never need a backup larger than that.

I have plenty of space with my 1TB, so 150% was not an issue for me

Woof, Woof - Dawg

 

[sparkie7]

Not the actual size of the drive, the actual space being used

Let's say I have a 250 drive but I am only currently using 140
I want my backup to hold that much and more (because I will be adding to the usage)
Also, Time Machine is incremental, and will add more and more space until it fills the drive (eventually) and then will begin deleting the oldest backups. I want space to grow and still have my backups relevant.

Same with CCCloner, if I am using 140 I want my drive larger because I will be adding files and the additional files will be added to the clone.

If you have a 250 and it is full, there is no reason to make a drive larger than the actual capacity of your drive, because it will never need a backup larger than that.

I have plenty of space with my 1TB, so 150% was not an issue for me

Woof, Woof - Dawg

LOL ok. I thought you were referring to the size of the drive. One more question, does timemachine automatically resize drive partition capacities on the fly?!?

 

[sickmacdoc]

LOL ok. I thought you were referring to the size of the drive. One more question, does timemachine automatically resize drive partition capacities on the fly?!?

No, Time Machine does not change partition capacity at all. All it does is keep on backing up until the allotted partition size is filled. It will then continue to backup by deleting the oldest backups in the set to create space for the newest ones.

 

[sparkie7]

ok thanks sickmacdoc for the confirmation. so wouldn't it make sense to set up or 'allocate' your target partition the same size (or larger) than your source drive? otherwise one will run out of space

my other question is should one set the target partition based on the 'box' size of the source drive or its actual capacity. ie I have "250GB" drive but after formatting it its Total Capacity in disk utility says 238.1GB. So should I set the target partition size at 240GB, 250GB, or 256GB? I'm think 240GB? unless Carbon Copy Cloner is copying invisible files totaling over and above this

 

[sickmacdoc]

ok thanks sickmacdoc for the confirmation. so wouldn't it make sense to set up or 'allocate' your target partition the same size (or larger) than your source drive? otherwise one will run out of space

my other question is should one set the target partition based on the 'box' size of the source drive or its actual capacity. ie I have "250GB" drive but after formatting it its Total Capacity in disk utility says 238.1GB. So should I set the target partition size at 240GB, 250GB, or 256GB? I'm think 240GB? unless Carbon Copy Cloner is copying invisible files totaling over and above this

OK I'm not positive that I understand which you are asking about partitioning for- Time Machine or CCC. If you are asking about CCC, then the partition will work fine with a partition of the same capacity as your hard drive and you will never run out of space. Note that when I say capacity means the actual usable space on the drive-- not what the marketing people's version of size is on the box label. Just do a "Get Info" on your drive, note the capacity and set up a partition that size and you will be fine. CCC does not copy additional files beyond the capacity of the drive so no worries. In reality, if space is tight the partition for CCC copying could be set several gigs smaller, as if your hard drive ever really gets filled up to capacity you will have a problem on your hands even running your computer! So if you have a 320Gb drive which has an approximate actual capacity of 297Gb, a CCC partition of 297Gb would be fine.

TM on the other hand should always be given a partition at least 1.5x the capacity of your drive to be backed up- and some recommendations are for 2x the capacity.

 

[sparkie7]

sorry, i meant CCC.

Thanks for the full explaination!