Author Topic: Minimum/Recommended Amount of Parity Storage for 30TB of Data?  (Read 525 times)

Offline Vapor1000

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Minimum/Recommended Amount of Parity Storage for 30TB of Data?
« on: December 08, 2017, 04:09:04 pm »
First off i am brand new to flexRAID and tRAID.
So i purchased a system that came with 25 TB of available storage, and about 6.4TB of Parity space.
The tRAID was configured as 4x4TB and 4x3TB dedicated to storage, and 1x4tb and 1x3tb dedicated to parity

I recently had one of the 3TB storage drives begin to fail, and so i removed the drive from the system entirely, and started the raid back up. I found after comparing files, that i was not able to access find or read some files that were on the 3TB drive that was removed. Granted i did not replace the 3TB drive with any other drives, i simply removed it for the time being as i intend on fully rebuilding the raid and blowing everything away and starting with new disks (Data already backed up on another system to prep for this). Do i have to replace the 3TB drive, and have it rebuild that drive from parity to have those files that have gone missing reappear on the raid? Or was the amount of parity space that was allocated to the 25TB of storage too small to account for everything?

If the amount of parity was too small, and that is why i am finding files missing that were confirmed to be on the bad drive that was removed, then how much space should i dedicate to parity if i am looking to up the storage to 30TB of data? I am looking at rebuilding the raid with 3x 8TB drives, and 2x 4TB drives for Data, and a minimum of 1 8TB drive for parity, and potentially up to 3x 4TB drives additionally dedicated to parity.

Can anyone 1. Confirm if i need to replace the drive removed and rebuild onto that drive for data to be present, ,and 2. Confirm how much parity data is necessary to cover for the loss of any 1 data drive with 30TB of data with the largest drive being 8TB.

Offline Brahim

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Re: Minimum/Recommended Amount of Parity Storage for 30TB of Data?
« Reply #1 on: December 08, 2017, 08:04:52 pm »
You should typically be able to access the data of the failed disk if the disk failed without corrupting its system.

Now, if the file system corrupted, all is not lost as you can still restore the failed disk and then run a file system recovery tool on the restored disk to get the files back: https://www.easeus.com/resource/raw-files-recovery-software.htm

« Last Edit: December 08, 2017, 08:06:48 pm by Brahim »

Offline Vapor1000

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Re: Minimum/Recommended Amount of Parity Storage for 30TB of Data?
« Reply #2 on: December 11, 2017, 11:58:36 am »
Good Info Thx,

What about the 2nd part of the question?

How much data is needed as parity to prevent loss with 30TB of data in tRAID?

Offline Brahim

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Re: Minimum/Recommended Amount of Parity Storage for 30TB of Data?
« Reply #3 on: December 11, 2017, 01:53:11 pm »
Good Info Thx,

What about the 2nd part of the question?

How much data is needed as parity to prevent loss with 30TB of data in tRAID?
It is not the amount of data nor disk count that matters.
The only thing that matters is that you have at least one disk for parity. You can protect an infinite number of disks and data with only one disk. You can further improve the tolerance level by dedicating two disks for parity. The only requirement is that the parity disk(s) must be as large or larger than any given single data disk.

In your configurations:
- 4x4TB only 1x4tb is needed for parity
- 4x3TB only 1x3tb is needed for parity

You could have also had one single configuration with all ten disks in a single array and only 1x4tb being needed for parity. However, having two smaller arrays as you have is better than a single larger one (i.e., eggs in two baskets vs eggs in a single basket).

Offline Zenitenut

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Re: Minimum/Recommended Amount of Parity Storage for 30TB of Data?
« Reply #4 on: December 27, 2017, 01:47:29 am »
I also want the same advice. I'm going to make a server. Should I Mini Spec?