On Fri, Jul 3 at 16:34, Erik Trimble wrote:
Ian Collins wrote:
Ross wrote:
[please keep some context for the email list]
Quick question to the more experienced guys here - how much space
would you end up with from 8 1.5TB drives in a raid-z array? Around
8-9TB?
Bearing in mind manufacturer TB != real TB, each drive will give about
1.35TB of formatted space, to you would get about 10.5TB.
As Ian pointed out, virtually all 1.5TB drives are actually
1,500,000,000,000 bytes in size, which equal about 1.364 TiB (to use the
stupid SI name).
Actually, pretty sure most manufacturers are settling on IDEMA LBA1-02
for sizing formulas.
LBA count = (97696368) + (1953504 * (Desired Capacity in Gbytes - 50.0))
So a "1.5TB" drive from that formula would be:
= 97696368 + (1953504 * (1500-50))
= 2930277168 LBAs * 512 bytes per sector = 1,500,301,910,016 bytes
If, for example, you look at the spec sheet on wdc.com for their 1.5TB
drive, they explicitly advertise the exact calculated sector count
above: 2,930,277,168
http://www.wdc.com/en/products/products.asp?driveid=575
There was tons of raid sizing wierdness issues in the past, but the
above is easy to check and is becoming very common. Every drive
vendor wants to be able to sell their drives into a raid array that
was originally populated with a competitor's devices.
--eric
--
Eric D. Mudama
edmud...@mail.bounceswoosh.org
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