How many disk can I use on RAID1?

jfk105 · Post by **jfk105** » Mon Sep 18, 2017 5:30 pm

Hello, I would like to know before I buy a new 4 bays nas if I can create an raid 1 array on 4 drives.
I know that total capacity will be the size of one drive but I hope that I have 4 mirrored drives with 3 disks tat can fault before everything dies. It is right? Is this possible with qnap nas?
Thanks in advance
J

MrVideo · Post by **MrVideo** » Mon Sep 18, 2017 5:50 pm

I have to assume that you did not "google raid" to find out what the various RAID types consist of and do.

The short answer to your question is NO. RAID1 only consists of two drives.

With a four-bay NAS, it is best to create a RAID5 of those four drives. RAID6 will give you the two drive fault tolerance. But, you give up 50% of the space. With RAID5 you can only lose one drive, but you only give up 25% of the space.

jfk105 · Post by **jfk105** » Mon Sep 18, 2017 6:00 pm

I have to assume that you did not "google raid" to find out what the various RAID types consist of and do.

Hello, I've read tons of pages about raid and I have doubts just because I found that QNAP says RAID 1 can works with a "minimum" of 2 drives so I guess it should works with more disks (2-4-6...).
I know if I have (e.g) 4 disk and each one is 4tb the size ot total is:
RAID 1 : 4 tb
RAID 5: 12tb
I'd like to have 8tb total size (made by 4 x 8tb drives) with 3 drives fault tolerance.Then I make external backup because I know that RAID is not a backup.

RAID 5 is not safe for me: I read bout URE and % of success into array rebulding and I'm scared about this.

Thanks, J

Don · Post by **Don** » Mon Sep 18, 2017 7:31 pm

Then use RAID 6. It will give you 2 drive redundancy. It is the best you will get on a QNAP.

jfk105 · Post by **jfk105** » Mon Sep 18, 2017 7:57 pm

But if I don't want splite data on drives (as raid5/6 does) I guess only Raid 1 can do it (mirror), or not?
So if possible with a 4 bays (Qnap) nas set raid 1 with 4 drives?
Thanks

Don · Post by **Don** » Mon Sep 18, 2017 7:59 pm

jfk105 wrote:But if I don't want splite data on drives (as raid5/6 does) I guess only Raid 1 can do it (mirror), or not?
So if possible with a 4 bays (Qnap) nas set raid 1 with 4 drives?
Thanks

Mr Video already answered. NO.

jfk105 · Post by **jfk105** » Mon Sep 18, 2017 8:03 pm

ok. I believe you and MRVideo but qnap site confused me: http://docs.qnap.com/nas/4.1/Home/en/in ... gement.htm

RAID 1 Mirroring Disk Volume: RAID 1 duplicates the data between two hard drives to provide disk mirroring. To create a RAID 1 array, a minimum of 2 hard drives are required. The storage capacity of a RAID 1 disk volume is equal to the size of the smallest hard drive.

A minimum,not a maximum, maybe is only an error or my interpretation is wrong, thanks.

storageman · Post by **storageman** » Mon Sep 18, 2017 8:25 pm

What you mean is referred to as an N-way mirror, Qnap only supports this in their QES models.

jfk105 · Post by **jfk105** » Mon Sep 18, 2017 8:53 pm

@storageman. I see, thank you.
Can I ask for advice here about a storage solution ?
What kind of raid and how many disks would you use for 8tb data storage (on Qnap nas)?
Obviously there will be an external backup (another nas or external usb dive).
Thanks a lot
J

storageman · Post by **storageman** » Mon Sep 18, 2017 9:00 pm

Seriously, listen to the previous advice, you don't need n-way mirror, it's an extreme requirement.
Use RAID 5 or 6 with 4 disks.
I suggest you go 4 x 4TB disks RAID 5 to give you 11TB useable.

jfk105 · Post by **jfk105** » Mon Sep 18, 2017 9:30 pm

and what do you think about 4 x 6TB RAID 6? (12tb data, 12 tb double fault tolerance) ?

storageman · Post by **storageman** » Mon Sep 18, 2017 9:45 pm

jfk105 wrote:and what do you think about 4 x 6TB RAID 6? (12tb data, 12 tb double fault tolerance) ?

Think what way? Only you know what you need. RAID 6, why not, if you can afford it.

MrVideo · Post by **MrVideo** » Tue Sep 19, 2017 4:43 am

jfk105 wrote:Hello, I've read tons of pages about raid and I have doubts just because I found that QNAP says RAID 1 can works with a "minimum" of 2 drives so I guess it should works with more disks (2-4-6...).

You've misread how RAID1 works on the QNAP NAS you are looking at. Read the manual for that particular model. Even better, google RAID and you'll find plenty of pages pointing out how RAID technology works. Specifically look at RAID1, RAID10, RAID5 and RAID6, the types used by QNAP.

MrVideo · Post by **MrVideo** » Tue Sep 19, 2017 4:45 am

jfk105 wrote:But if I don't want splite data on drives (as raid5/6 does)

It is because of that very RAID operation that can result in saving your A$$, specifically your data. Even then, you still need to do external backups.

MrVideo · Post by **MrVideo** » Tue Sep 19, 2017 4:46 am

jfk105 wrote:RAID 5 is not safe for me: I read bout URE and % of success into array rebulding and I'm scared about this.

Many of those articles are out-and-out wrong. They are spreading FUD.

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