> For the complete documentation index, see [llms.txt](https://docs.ionos.com/cloud/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ionos.com/cloud/backup-and-storage/network-file-storage/overview/tech-specification-limitation.md).
# Technical Specifications and Limitations
Network File Storage (NFS) specifications explained: throughput, IOPS, latency, resilience, availability, and known limitations on IONOS CLOUD
## How fast is Network File Storage (NFS)?
NFS runs on SSD Standard in shared mode. All metrics scale linearly with provisioned capacity.
{% hint style="info" %}
**Note:** These benchmarks were measured using the iozone tool on a 4 TiB SSD Standard cluster, with 5 clients each generating 10 GB of I/O per host. Results are averaged across 20 runs, with caches cleared between runs and outliers excluded.
{% endhint %}
### What is NFS throughput?
Peak sequential throughput is \~370 MB/s read and \~319 MB/s write per TiB.
| Metric | Per TiB |
| --------------------- | ---------- |
| Peak sequential read | \~370 MB/s |
| Peak sequential write | \~319 MB/s |
A 4 TiB cluster delivers \~1,480 MB/s sequential read / \~1,275 MB/s sequential write.
Read throughput is buffer-sensitive: when the active dataset exceeds the block storage read buffer, sustained throughput drops to \~850 MB/s (1 MiB block size, 4 TiB). Write throughput is not buffer-sensitive.
### What are NFS IOPS?
A 4 TiB cluster sustains \~24,000 aggregate read IOPS and \~18,000 aggregate write IOPS, at a 4 KiB block size.
| Metric | Per Client | Aggregate per 4 TiB |
| ---------- | ---------- | ------------------- |
| Read IOPS | \~4,000 | 24,000 |
| Write IOPS | \~470 | 18,000 |
Reaching aggregate write IOPS requires \~372 concurrent operations at \~20 ms latency — above the default NFS RPC slot table limit (64–128 per mount). Per-client figures assume a single mount.
### What is NFS latency?
Mean latency is 2.8 ms for reads and 20.7 ms for writes.
| Operation | Mean | Median | P99+ (worst observed) |
| --------- | ------- | ------- | --------------------- |
| Read | 2.8 ms | 2.8 ms | 292 ms |
| Write | 20.7 ms | 21.9 ms | 2,187 ms |
Write latency is synchronous to an active-passive replicated backend. P99 spikes correlate with block storage flush and GC events.
### Does NFS use NIC Multi-Queue?
Network File Storage (NFS) activates [NIC Multi-Queue](/cloud/network-services/vdc-networking/nic-multi-queue.md) by default on clusters with at least two CPU threads (two cores, or one core with hyperthreading). This distributes network traffic across multiple queues to improve throughput and reduce latency, delivering a throughput improvement of approximately 10% at two cores.
Unlike the general NIC Multi-Queue feature for VMs, NFS activates this automatically and requires no configuration from the user.
## How resilient is NFS?
Storage runs across two servers with automatic failover. Each server uses hardware or software RAID.
## How does NFS secure data?
NFS is based on Block Storage and inherits its data security properties, including encryption at rest and secure deletion. For details, see [Data Security](/cloud/backup-and-storage/block-storage/overview/data-security.md).
NFS also supports squash security, a built-in mechanism that reduces the risk of unauthorized root-level access from a client machine to the NFS server. Enabling root squash prevents superuser privileges for the root user on a client machine, which also helps prevent potential attacks if the client machine is compromised.
## Where is NFS available?
NFS is available in the following regions:
* Berlin, Germany
* Frankfurt, Germany
* Paris, France
* London, Great Britain
* Logroño, Spain
* Las Vegas, United States
* Newark, United States
* Lenexa, United States
For region-specific API endpoints, see [Regional endpoints](/cloud/backup-and-storage/network-file-storage/api-how-tos.md#regional-endpoints).
{% hint style="info" %}
**Note:** NFS will soon be available in the Worcester, United Kingdom, region.
{% endhint %}
## What are the storage specifications of NFS?
* **Cluster size:** Ranges from 2 TiB to 42 TiB, in 1 TiB increments. All provisioned capacity is fully usable; no space is reserved for system overhead or performance headroom.
* **Share quota:** Each share supports an optional quota in MiB that caps the amount of data it can store. Set the quota to 0 to disable it for that share.
## What are the known limitations of NFS?
The following constraints apply:
* Cluster size can only be increased after provisioning, never decreased
* Write IOPS are constrained by synchronous write latency (\~20 ms); achieving aggregate write IOPS requires concurrency levels that may exceed default NFS client RPC slot table limits
* Not suitable for synchronous write workloads with tight timeout requirements
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