SSD Capacity

[revolutn]

I assume that the answer to this is yes, but for the sake of being thorough:

Do manufacturers still insist on expressing the capacity of SSD's in the same way they did traditional HDD's?

I.E. in Gib instead of GB?

If I wanted to figure out the actual formatted usable space on say a SDD marketed and sold as 40GB, would that calculation still be:

40 * 1,000,000,000 / 1024 ^ 3

For a rough capacity of 37.2GB before OS installation?

I'm slightly embarrassed to have to ask this, but since I've not purchase one yet and I can't recall actually seeing the exact capacity discussed in an article I just wanted to be sure so I can calculate my actual sweet spot in terms of need vs $/GB.

Intended for a single bay laptop so no room for a second HDD, though I can use networked storage to help. My current W7 64 + Essential Apps weighs in at about 24GB w/o data files.

Thanks,
Rev

 

[Ben90]

Yes, however I know OCZ (and possibly other companies) rounds down. E.g. They advertise their 64Gib drive as 60GB.

 

[revolutn]

Yes, however I know OCZ (and possibly other companies) rounds down. E.g. They advertise their 64Gib drive as 60GB.

Argh! So inconsistency amongst the many vendors, just great, one less thing this emerging market needs!

Correct me if I'm wrong though, but based on your description, I would think OCZ is marketing it as 60GB based on not the formatted space, but on the available space after taking into account their 'spare' NAND used for like caching and the like that every SSD actually has 'more' memory than the user accessible space, no?

 

[vj8usa]

Correct me if I'm wrong though, but based on your description, I would think OCZ is marketing it as 60GB based on not the formatted space, but on the available space after taking into account their 'spare' NAND used for like caching and the like that every SSD actually has 'more' memory than the user accessible space, no?

I don't know how it works with OCZ's drives, but I know intel's 80GB drives, for instance, actually have 80GB of total flash in them but only make 80GiB usable at any given time. The rest is reserved as spare area.

See here:
http://www.anandtech.com/storage/showdoc.aspx?i=3631&p=7

 

[jkroeder]

I have both a 60GB OCX Vertex and an Intel X25-M 80GB.

The Vertex usable space actually is 60GB while the X25-M is 74.4GB

 

[vj8usa]

I have both a 60GB OCX Vertex and an Intel X25-M 80GB.

The Vertex usable space actually is 60GB while the X25-M is 74.4GB

Any idea how much extra flash it has on it as spare area, if any? I vaguely remember a thread on the OCZ forums where someone said they couldn't fill up more than 50GB of their 60GB OCZ drive, but I'm sure that was a fluke.

 

[jiffylube1024]

Do manufacturers still insist on expressing the capacity of SSD's in the same way they did traditional HDD's?

I.E. in Gib instead of GB?

If I wanted to figure out the actual formatted usable space on say a SDD marketed and sold as 40GB, would that calculation still be:

40 * 1,000,000,000 / 1024 ^ 3

For a rough capacity of 37.2GB before OS installation?

Hi Rev. You are Correct for every manufacturer except OCZ, who add 2GB for every 30GB of space on their drives for a more accurate picture of useable space.

So, for example, an 80GB Intel X25-M has approximately 74.5GB of useable space since their 80GB is 80,000,000,000 bytes.
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Note: On the uber high End OCZ Vertex LE (limited Edition) 100GB and 200GB drives, OCZ rates their drive conventionally; a "100GB" drive has about only 93.1GB of useable space.

An OCZ 30GB drive is really 32,000,000,000 bytes, 60GB OCZ is 64,000,000, etc. So, an OCZ "30GB" drive has about 29.8GB of useable space; a "60GB" OCZ drive has about 59.6GB, etc.

 

[jiffylube1024]

Any idea how much extra flash it has on it as spare area, if any? I vaguely remember a thread on the OCZ forums where someone said they couldn't fill up more than 50GB of their 60GB OCZ drive, but I'm sure that was a fluke.

I can't remember the exact figure, but I heard the extra flash is about 5-10% of the total capacity, depending on manufacturer. I think the OCZ LE drives may actually have more memory allocated as spare/backup, but I can't find the link.

This article claims that the Intel X25-M actually has 80GB (85,899,345,920 bytes) of storage:

http://www.anandtech.com/storage/showdoc.aspx?i=3631&p=7

So, Intel apparently puts the correct amount of flash in their drives (80GB = 80.0GB of total flash memory) but uses the difference between GB and GiB as spare area. So in this case, on an 80GB intel drive, 5.5GB is used for spare area (7.4%), and the rest is useable disk space - 74.5GB. On a 160GB Intel drive it would be 11GB of spare area, 149GB useable.

Regarding not being able to fill up a 60GB OCZ drive - that sounds bogus to me. I've got two 30GB OCZ drives (a Solid 2 and a Vertex) and formatted they have about 29.8GB of space. I've filled one of them to 99% before, about 29.7GB of data just to see if it could. No problems whatsoever.
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The big issue with SSD is that it starts to slow down as the drive fills up. TRIM helps alleviate this problem greatly, but an SSD with data on it will not be as fast as one with no/virtually no data on it.

I've heard that it's best to keep about 10-20% of the SSD free for best performance. That's one of the reasons why it's so tough using only a 30GB drive; in order to follow this advice, you need to leave at least 3-6GB free; that leaves room for Windows, a few programs and little else. The other stuff needs to go on a separate drive.

That is one of the reasons why 60-120GB is desireable for an SSD, even if it's just going to have a few programs on it and be used as a boot drive. You get to leave more free space on the disk for wear leveling, copying and caching files, etc.