The reason I wrote this article was a customer who wanted to know whether it would cost less to store a petabyte of data in the cloud or on-premises for 3 years. My first thought was the cloud – I was only looking at the cost of storing the data, and the prices below exclude the egress and data retrieval charges that make cloud storage more expensive.
In the cloud, storing 1PB in Microsoft Azure Blob Storage (UK South) costs around £8,300 a month on the Cool tier and £14,300 a month on the Hot tier at list prices – roughly £298,000 to £514,000 over 3 years, before any data transfer or retrieval charges. On-premises, the cost is mainly the storage system, its support and the power to run it.
Azure list prices checked 21 October 2026.
We used Microsoft Azure Blob Storage in the UK South region, pay-as-you-go list prices in pounds, for 1PB (1,048,576GB – the way Azure counts storage).
| Tier | Price per GB per month | Per month for 1PB | Over 3 years |
|---|---|---|---|
| Hot (LRS) | £0.0145 for the first 50TB £0.0139 for the next 450TB £0.0133 over 500TB | £14,284 | £514,223 |
| Cool (LRS) | £0.0079 | £8,284 | £298,215 |
Read more: Hidden cloud storage costs in the UK
On-premises, you pay for the storage system once, plus support and the power to run it. There are no charges for reading or moving your own data.
Example: a system drawing 2kW, running for 3 years at 35p per kWh, costs 2 × 24 × 365 × 3 × £0.35 = £18,396 in electricity.
Seagate's Exos EP5U84 holds up to 1.3PB in a single 5U enclosure, so one system covers a petabyte. It uses Improved ADAPT data protection for faster drive rebuilds.
Get a petabyte storage quoteWhen we first ran this comparison, the on-premises system was a Seagate Exos CORVAULT with 2PB of storage and 3 years' 24x7 support for £50,000. With £18,396 of electricity, the total was £68,396 over 3 years – for twice the capacity of the cloud figures, and without any charges to get the data back.
Seagate Exos CORVAULT is no longer available. Today we would quote the Seagate Exos EP5U84 – contact us for a current price.
In order for us to compare an on-premise solution vs a cloud solution we need to establish a few criteria. We chose to use Microsoft Azure Blob Storage for both Hot and Cool pricing and purchased a 3-year reserved blob – Flat Namespace – LRS – UK South:
https://azure.microsoft.com/en-gb/pricing/details/storage/blobs/
The quoted price surprised me as it was considerably more than I had been expecting. I then compared this to a Seagate Exos® CORVAULT™ populated with a total of 106 Exos drives!
Now we get the surprising part, the price for the Seagate Exos CORVAULT with 3 years 24x7 support and maintenance is £50,000 and it fits in 4U!
So how much does it cost to store a petabyte of data on-premise including energy consumption?
The total cost is a £68,396 for 3 years!
On-premise storage worked out to be.
This comparison really did throw up an unexpected result as unlike the cloud you don't pay any additional charges data transfer charges.
The Seagate CORVAULT price is for 2PB of storage – twice the capacity of the cloud figures above – so the real saving is even bigger.
See our petabyte storage solutions or call 01256 331614 to talk through your options.
Get a current petabyte quote| Advantages | Disadvantages |
|---|---|
| No infrastructure to worry about | Increasing costs |
| Easy to scale | Additional Charges |
| No energy bills to pay | WAN Performance |
| Vendor Lock-In | |
| Data Security | |
| Downtime |
| Advantages | Disadvantages |
|---|---|
| Performance | Rack space, power, cooling |
| Fixed costs | Back-end infrastructure |
| No additional charges | |
| Control | |
| No WAN costs |
A petabyte is about a thousand terabytes. Microsoft Azure counts 1PB as 1,048,576GB.
In Microsoft Azure Blob Storage (UK South), 1PB costs around £8,300 a month on the Cool tier and £14,300 a month on the Hot tier at list prices checked 21 October 2026, before data transfer and retrieval charges.
It can be over several years, because you pay for the system once and there are no charges to read or move your own data. When we first ran this comparison, on-premises cost £68,396 over 3 years against £202,536 to £370,332 for Azure reserved capacity at the time.
As well as storage, cloud providers can charge for data transfer out (egress), data retrieval on cooler tiers, and read and write operations.
A Seagate Exos EP5U84 holds up to 1.3PB in a single 5U enclosure.
Contact us with how much data you need to store and for how long, and we will give you a current UK quote.
Tell us how much data you need to store and for how long, and we will compare cloud and on-premises costs for you.
Prefer email? Write to solutions@fortunadata.com
