Raid5 - Can I start with 2 drives then add 3rd later?

[droiduser22]

I am trying to help a friend. He does photography. Serious hobby.

Baremetal i5 6th gen (6400)

16gb ram.

going to add 2 512gb for cache drives 

Is this overkill?

 

The issue is:

He has 2 10Tb WD red drives.

Can we use this setup and when he gets a third drive simply add it to the array and make it raid5 OR does raid5 and all 3 drives needed from first setup?

Can we add a 20Tb (for 3rd drive) and partition/volume for 10TB and use remainder space for other things?

Will splitting the 20TB drive let it work as if we had 3 10Tb drives? Or for raid5 to work they all have to be 10Tb (same size drive)?

 

Please let me know so I can proceed. I hope I provided enough details.

THANKS!

D.

[bermaa]

if you choose SHR yes, im starting with 1 drive, then slowly adding drive. now my machine has 4 drive.

just note when adding the 2nd drive, the capacity will not increase as it is used as protection.

[droiduser22]

46 minutes ago, bermaa said:

if you choose SHR yes, im starting with 1 drive, then slowly adding drive. now my machine has 4 drive.

just note when adding the 2nd drive, the capacity will not increase as it is used as protection.

Thanks for the info. I understand about the capacity.

 

[Carlxs]

SHR is not required. When You add 2nd drive, Synology allows You to turn it into RAID 1 (mirrored drives). When You add 3rd one, Synology allows You to change array to RAID 5.

Edit:

If You add only 20TB to 2x10TB, SHR will not help You. It would take effect only when You add 4th drive (20TB), then You would have 40TB redundant space from total 60TB on all drives. I.e. Your array would be better protected with 6x 10TB drives in RAID 6 (up to 2 drives failure in same time).

Just be aware, when You split 20TB 3rd drive to 10+10TB and one add to RAID 5, remaining 10TB (will be less, do not be surprised) will be UNPROTECTED against drive failure.

Edited November 10 by Carlxs
Additional information

[Trabalhador Anonimo]

To use different size of drives, you should use SHR, other wise, you will loose a lot of space. As said before, Synology let you change the raid type anytime you want. You can start as raid 1 (2x HDD same size) but only 10Tb of usable space and when you add the new driver, with different size, you can change to SHR.

Split the driver manually do not work. Synology will re-split as it fit for the raid system you choose andthe not used space will be unusable (invisible) to the system.

[DSfuchs]

On 11/3/2024 at 6:28 PM, droiduser22 said:

I am trying to help a friend. He does photography. Serious hobby.

Baremetal i5 6th gen (6400)

16gb ram.

going to add 2 512gb for cache drives 

Is this overkill?

 

The issue is:

He has 2 10Tb WD red drives.

Can we use this setup and when he gets a third drive simply add it to the array and make it raid5 OR does raid5 and all 3 drives needed from first setup?

Can we add a 20Tb (for 3rd drive) and partition/volume for 10TB and use remainder space for other things?

Will splitting the 20TB drive let it work as if we had 3 10Tb drives? Or for raid5 to work they all have to be 10Tb (same size drive)?

 

Please let me know so I can proceed. I hope I provided enough details.

THANKS!

D.

The truth is:
The extremely slow RAID5 starts with 3 drives. It can be even drastically slower with the proprietary SHR and >=2 volumes.
So only RAID1 and pairwise expansion to RAID10 is an option. Since the performance is excellent under RAID1, 4 and 10, cache drives are superfluous. They would also have to be enterprise SSDs with SLC chips, which would cost several thousand. Normal SSDs would wear out quickly, especially under RAID5.

Pushing up IOPS, my favorites are there 2x additional Intel Optane Memory 16GB, M.2 2280, MEMPEK1W016GAXT. Less is more.

 

Everything else just benefits the manufacturer's, and gives the user a fragile and slow system of their own making.

 

The fastest and by far the most cost-effective is RAID4. I already have a write speed of >400MB/s with 3 drives, but this is also the case if one drive has failed. But since this would drastically reduce Synology's profits, the GUI does not offer it. However, it is very easy and quick to set up via the command line.

 

When it comes to real data security, a system must have the ZFS file system build in. Synology is the wrong choice, as it is unfortunately not supported by them yet.

Edited November 22 by DSfuchs

[droiduser22]

On 11/22/2024 at 11:07 AM, DSfuchs said:

The truth is:
The extremely slow RAID5 starts with 3 drives. It can be even drastically slower with the proprietary SHR and >=2 volumes.
So only RAID1 and pairwise expansion to RAID10 is an option. Since the performance is excellent under RAID1, 4 and 10, cache drives are superfluous. They would also have to be enterprise SSDs with SLC chips, which would cost several thousand. Normal SSDs would wear out quickly, especially under RAID5.

Pushing up IOPS, my favorites are there 2x additional Intel Optane Memory 16GB, M.2 2280, MEMPEK1W016GAXT. Less is more.

 

Everything else just benefits the manufacturer's, and gives the user a fragile and slow system of their own making.

 

The fastest and by far the most cost-effective is RAID4. I already have a write speed of >400MB/s with 3 drives, but this is also the case if one drive has failed. But since this would drastically reduce Synology's profits, the GUI does not offer it. However, it is very easy and quick to set up via the command line.

 

When it comes to real data security, a system must have the ZFS file system build in. Synology is the wrong choice, as it is unfortunately not supported by them yet.

Thanks for the detailed info. I think I understand it.

 

On a slightly different note.

He's using 2 ten TB drives that mirror.

He wants to add 1 twenty TB drive as it's own volume. NOT part of the current RAID of the other 2 drives.

He will later add another 20TB drive and mirror the 2 twenty's.

 

So there will be a RAID array with the 2 ten TB drives.

And later a separate array with 2 twenty TB drives BUT to start there will only be 1 twenty TB drive that is NOT part of the first array with the 2 ten TB drives.

 

Is this possible?

 

 

 

[DSfuchs]

On 11/10/2024 at 3:54 PM, Trabalhador Anonimo said:

To use different size of drives, you should use SHR, other wise, you will loose a lot of space. As said before, Synology let you change the raid type anytime you want. You can start as raid 1 (2x HDD same size) but only 10Tb of usable space and when you add the new driver, with different size, you can change to SHR.

Split the driver manually do not work. Synology will re-split as it fit for the raid system you choose andthe not used space will be unusable (invisible) to the system.

That's not true, there's no getting away from SHR. You were lured into the manufacturer's trap. The hurdle to switch to another manufacturer has then been made as high as possible.

Edited November 25 by DSfuchs

[DSfuchs]

12 hours ago, droiduser22 said:

Thanks for the detailed info. I think I understand it.

 

On a slightly different note.

He's using 2 ten TB drives that mirror.

He wants to add 1 twenty TB drive as it's own volume. NOT part of the current RAID of the other 2 drives.

He will later add another 20TB drive and mirror the 2 twenty's.

 

So there will be a RAID array with the 2 ten TB drives.

And later a separate array with 2 twenty TB drives BUT to start there will only be 1 twenty TB drive that is NOT part of the first array with the 2 ten TB drives.

 

Is this possible?

 

 

 

This is possible and makes sense, as the second volume can be used for backup and recoverable data, among other things.

The new drive must be created as a "Basic" type (RAID1 with single drive).

Edited November 25 by DSfuchs