How to add larger disk drives than what is installed


emt

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Have version 6.2 installed

I could not find this answer so I'm asking.

Currently have 4 3TB drives for data  and the Cache and Parity Drives are also 3TB.

I need to increase the storage by install 6TB or 10TB drives.

Do I only need to replace the Parity drive and one data drive at a time or does the Cache drive need to be replaced too?

2nd question:

What is the best way of doing this, just remove a 3TB dive and install the new on, or can I somehow copy old drive to new drive?

Larry

 

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The cache drive does not have to be increased in size - it can be any size - bigger or smaller than parity. But typically people use SSD drives of ~250G or 500G.

 

Are you wanting to swap out an existing disk, or add a new disk to the array?

 

It is recommended that any new disk be precleared. The fact that preclear leaves a disk in a zeroed state is useful some of the time. But the fact that preclear tests the drive is the reason you'd preclear it even if you don't need it cleared.

 

If you are wanting to add a new larger parity, and move your parity disk to become an array disk, that is doable in one step.

 

If you want to swap out a disk, that can be done in one step.

 

If you want to swap out multiple disk, you can build them one at a time.

 

I'd recommend you run a parity check before doing any drive exchanges, to make sure all is running smoothly and ensure parity is perfect before you start.

 

I'll also recommend being extremely careful if you are opening your case to swap disks around or insert a new one. The risk of knocking something loose is very high - happens all the time here. And with a marginal connection, the chance of a disk swap / rebuild failing, and another disk dropping from the array are quite high.

 

If you post back exactly your current configuration and desired new configuration, people can suggest a process that introduces least risk of data loss and is the quickest. Sometime they are not the same.

 

Good luck! 

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What I have installed in this server:

Parity Drive  3TB

Cache Drive  3TB

5 Data Disk each is 3TB for a total of 15TBs.

 

So your saying that the Cache drive can be  SSD drives of ~250G or 500G?

So that's good to know How do I replace the Cache drive for smaller SSD and then use that drive as a data disk?

 

Also not sure what size of hard drives to purchase at this time, 6, 8 or break down and spring for a 10TB for the Parity now and start with replacing the 3TB with 6 or 8TB?

Larry

 

 

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  • 2 weeks later...
On 3/31/2017 at 9:55 AM, emt said:

 

So your saying that the Cache drive can be  SSD drives of ~250G or 500G?

 

Also not sure what size of hard drives to purchase at this time, 6, 8 or break down and spring for a 10TB for the Parity now and start with replacing the 3TB with 6 or 8TB?

 

 

The size of the new parity disk to use is a chicken vs. egg question - the parity drive needs to be as large as the largest disk on the array.   So of course bigger is better in terms of future proofing your drive replacement as your array grows over time.   for the 4 vs 5 vs 8 vs 10 TB discussion it's perhaps more of a value proposition for you than anything, unless you have strict storage requirements to hit or a set number of drives you have room for.  

 

For example you could go for better value with a 4 or 5TB parity for now, and unless you're prodigious with the rate of growth of your data, you can then always move that 5TB onto the array and replace it as needed (or as you find a good deal) gaining array space along the way -- then if/as you can afford larger drives as you move thru that replacement cycle you move the old parity drive over into the array and newest largest drive becomes parity.   So both the parity and array grow "organically".   Of course then we bump against the space in your case / options for your motherboard, etc.   There are plugins to reallocate the data and balance the shares over the drive pool for you for this type of strategy.  Or of course you can bite the bullet and go big on parity.   Think of the lifespan of the devices of course when making the value calculation, IE will your 10TB drive be old by the time you can afford enough of them to fill up your array?   If so it's probably overkilll 

 

However, consider splurging also on redundancy - IE 2 parity drives, meaning you can survive 2 simultaneous drive failures on the array without losing data.   For Noobs (error prone while mucking about with changing out hardware, esp. in a data loss "emergency" scenario where replacing one drive leads to error or trauma that leads to another...), And for the average home user with cheaper/older/less redundant hardware, less sophisticated UPS / power conditioning and less experience knowing what NOT to do... Well, again a multi-device failure (or "assisted failure" as I like to think of it) may be where you want to pony up and guard against.   There will almost always be a single point of failure somewhere (even fat fingering a single command @ Amazon can take down the East coast as we just found out), so the sanity check is to decide up front what level of risk your comfortable with and where (which component) worries you the least and work toward that.   THAT in many cases will provide the answers you seek.......

 

A final point to drive home about the Cache drive - if you use more than one cache drive UnRaid can set up a mirrored array between the two (or more) drives so that there is some improved protection against short term data loss, IE information that you've just pushed to the server (since that data typically sits on the cache drive until the mover program sweeps it into the array).    So the Cache mirror drive and Parity can work in complement to minimize data loss - also helpful with things like brownouts / power outages (failure during a disc write due to the nature of how SSD's work - and Btrfs as well).    Also of Course if you keep your VM's and Dockers stored on the cache it allows a way of backing that up automatically.

 

The size of the cache drive(s) / whether to use one is up to you....  UnRaid  is your oyster....

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Swapping SSD for parity would be a good move IMO. Adding the 3T cache to array would just require preclearing it and then easy add.

 

Not sure where you are going with your array. Could be that extra 3T will keep you going for a year or more. Or it could be you'll fill it in a month.

 

If you are going to upsize parity, might consider 8T. Seems to be the sweet spot. The 8T Seagate archives (which if you are willing to harvest from external enclosures, can be bought for $190), are the best deal going, maybe the best deal ever. They would be my recommendation at this point. The first one would be needed to upsize parity, but additional ones would give you  to 8T a pop.

 

10T Ironwolf - $369 - $36.90 / TB

8T Seagate - $189 - $23.64 / TB

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