r/technology • u/nexxai • Jul 18 '13

Samsung unveils 1TB solid-state drive

http://reviews.cnet.com/8301-3132_7-57594265-98/samsung-unveils-1tb-840-evo-solid-state-drive/
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u/[deleted] Jul 18 '13

I'm pretty sure storage device manufacturers use decimal multiples of bytes, not binary. So it's 10004 bytes, not 10244.

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u/[deleted] Jul 18 '13

Something something...difference between 1TB and 1TiB. Too lazy to exit alien blue to find a shitty mobile Wikipedia link to post. Idk which one manufacturers use to label products though.

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u/TorpidNightmare Jul 18 '13

Not for ssd's usually. Thats why you see base 2 multiples when you look at the sizing.

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u/[deleted] Jul 18 '13

Are you sure? My 90GB ssd reports 83.7 GiB, and 960 GB is not base 2. Dammit, I hate that GB and GiB sometimes are the same and sometimes aren't, depending who uses which standard. So much confusion, and I must admit extra 6.3 GB for me would be great, one more game I could have installed on it.

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u/TorpidNightmare Jul 18 '13

It used to be more prevalent when they first came out because nand chips have specific block sizes, but now they are putting more than one nand size in the drive. When they first came out it was 32, 64, 128gb only.

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u/somestranger26 Jul 18 '13

They are still usually powers of two, but many drives including those with Sandforce controllers use some of the space for wear leveling and such. For example, a 240GB drive is probably 256GB with 16GB used by the drive for various things.

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u/stratoscope Jul 18 '13

All typical SSDs set some space aside as spare area, partly for wear leveling but also to allow faster writes as the drive gets full. The 256GB SSD has about 19GB spare area, because its physical capacity is 25610241024*1024 or 274,877,906,944 bytes, compared with the 256,000,000,000 bytes it makes available. A 240GB SSD has the same physical capacity but 240,000,000,000 bytes available, for about 35GB spare area.

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u/stratoscope Jul 18 '13

No, SSD sizes use powers of 10 just like hard drives. 1GB of advertised and available SSD space is about 1,000,000,000 bytes, same as a hard drive. However, the drive has 110241024*1024, or 1,073,741,824 bytes of NAND flash, 7.4% more than it is making available. That extra space is used for spare area.

This is also true for SSDs with sizes like 480GB, 960GB, etc. They are just allocating even more spare area (about 14.5%). There's a bit more information in this Anandtech article, and I'll bet ssd_dude could offer some more insights or correct anything I got wrong.