A database-driven site spends much of its time doing small, random reads and writes to disk. How fast those complete, and how many can happen per second, is set by the drive technology and any cap the host places on it.
HDD, SATA SSD, NVMe
| Type | Random reads per second | Feels like |
|---|---|---|
| Spinning HDD | Hundreds | Fine for backups and archives, poor for a live database |
| SATA SSD | Tens of thousands | Good for most sites, the old default |
| NVMe SSD | Hundreds of thousands to millions | Headroom for busy databases and many files at once |
For a small site the difference is minor. It shows up when many visitors, a big database or lots of files push the disk hard at the same time. That is when SATA queues and NVMe keeps up.
IOPS: the cap that really bites
IOPS means input/output operations per second: how many individual read or write actions the disk handles. Many VPS and cloud plans put a limit on it, for example 3,000 or 5,000 IOPS, even on NVMe hardware. Hit that ceiling and disk operations start waiting, which looks exactly like a slow database.
This limit is often not on the pricing page. Ask for it. A plan with fast hardware but a low IOPS cap can perform worse under load than a plan with a higher cap on slightly slower disks.
Where you feel slow storage: the site is quick with one visitor and drags when several hit a search page, a filtered shop view or the admin area at once. Those pages do many small database reads, and a disk that is capped or slow turns that into a queue.
What to look for
- NVMe storage stated plainly, not just "SSD"
- The IOPS limit for the plan, in writing
- Local NVMe rather than network storage for anything database-heavy, unless the network storage has high guaranteed IOPS
- Enough size headroom that you are not near full, because full SSDs slow down
- Backups on separate storage, so a restore does not compete with the live disk
Size versus speed
Storage size only matters when you are close to filling it. Storage speed matters every time the database is queried. If you are choosing between more gigabytes and faster or less-capped disk, and your site is database-driven, take the speed.
Mahdi Hassan · Web Developer & Site Speed
On a VPS, ask two questions: is it local NVMe, and what is the IOPS limit. A cheap plan on capped network storage can feel slower than a slightly pricier one on uncapped local NVMe, and you will only find that out under real traffic if you did not ask first.
Illustrative example
A shop that slowed down only on filter pages
Picture a store that is fast on product pages but sluggish whenever shoppers use the category filters, which run many small database reads. The plan said NVMe.
The plan also had a low IOPS cap that the filter queries hit during busy periods. Moving to a tier with a higher cap, same disk type, cleared the slowdown.