How much space is free for a new 256 gig hard drive on macbook retina ?

[anonymous4a]

Just curious, I have a 256 gig hard drive on my macbook retina but it reads that I have 220 gigs free, and that the total space is 250 gigs.. shouldn't it read 256 gigs ? And the 30 gigs already used.. is it the OS ?

This is how it reads..

Macintosh HD:

Available: 220.72 GB (220,716,748,800 bytes)
Capacity: 250.14 GB (250,140,434,432 bytes)
Mount Point: /
File System: Journaled HFS+
Writable: Yes
Ignore Ownership: No
BSD Name: disk0s2
Volume UUID: 938B9109-A4F4-3EE8-BDD9-143AA04674B1
Physical Drive:
Media Name: APPLE SSD SM256E Media
Medium Type: SSD
Protocol: SATA
Internal: Yes
Partition Map Type: GPT (GUID Partition Table)
S.M.A.R.T. Status: Verified

 

[anonymous4a]

anyone ?

 

[KPOM]

anyone ?

I don't know about the stock free space since I've always migrated right away, but I've had 2 MacBook Airs with the 256GB SSD and now the rMBP. All have had 250GB of total space. With an SSD, the advertised capacity is the total capacity of 256GB. However, all SSDs set aside a certain percentage of the total space (called overprovisioning), since an SSD's controller needs some unusable space in which to conduct its normal activities. For instance, since each cell in an SSD can only be written to a finite number of times (roughly 3000), an SSD will move data around a bit if it detects that certain cells are being used a lot more than others. It uses the overprovisioned space for these activities.

250GB is normal for the 256GB drives that Apple uses. 121GB is normal for the 128GB drives that they use.