TB Hard drives in Synology Disk Station DS409

Hello experts,

I have purchased a synology ds409 from newegg.com and four 1.5 TB hard drives.

The hard drives show up as 1.36TB, and when i formatted them into a single RAID5 volume, i only have 4TB total on the volume.

Where did the other 2TB of space go? i know some went to the raid config, but why does only 1.36 show up? That's like 140 x 4 = 560GB's.. thats a ton of drive space that is missing.
LVL 1
jaysonfranklinAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

simsjrgCommented:
That's about right then. Essentially with RAID 5 you get the combined total drive capacity -1 disk so...

4 x 1.5TB = 6TB - 1.5TB = 4.5TB. This is the RAW capacity so the ~4TB formatted capacity you are seeing is correct.
0
jaysonfranklinAuthor Commented:
So RAID 5 uses 1 disk for the striping and parity, but the space for this is distributed over an entire disk?

why is the raw capacity for a 1.5 tb drive only 1.36? That's 140GB which is a lot of space and more than my internal hdd on my computer..
0
simsjrgCommented:
>> So RAID 5 uses 1 disk for the striping and parity, but the space for this is distributed over an entire disk?

Not exactly... the parity is spread over all of the drives that if any one drives fails you can recover without and data loss.

>> why is the raw capacity for a 1.5 tb drive only 1.36? That's 140GB which is a lot of space and more than my internal hdd on my computer..

This goes back to the fact that manufacturers sell drives and market a GB as being 1000MB when in fact it's 1024MB. I believe it's somewhere in the market of ~74MB or ~75MB you "lose" per GB.

I wish I could find the site to reference for that...
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Determine the Perfect Price for Your IT Services

Do you wonder if your IT business is truly profitable or if you should raise your prices? Learn how to calculate your overhead burden with our free interactive tool and use it to determine the right price for your IT services. Download your free eBook now!

simsjrgCommented:
Anything else we can help you with regarding this?
0
jaysonfranklinAuthor Commented:
guess not.. didn't know if you were still trying to locate the link. No worries. Thanks a bunch for your help.
0
oidzCommented:
Another reason for the loss of space is that the Synology NAS needs to install it's 'OS' onto the drives in order for it to function. This creates a series of partitions which swallows up a reasonable amount of space. It's usually around the 2GB per disk level, so you would be looking at losing another 10GB or so there.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Storage

From novice to tech pro — start learning today.