# Technical Specifications and Limitations

## Performance

Runs on SSD Standard in shared mode. All metrics scale linearly with provisioned capacity.

{% hint style="info" %}
Benchmark: iozone, 4 TiB SSD Standard, 5 clients, 10 GB/host, 20 runs, caches cleared between runs, outliers excluded.
{% endhint %}

### Throughput

| 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.

### IOPS (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.

### Latency

| 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.

## Resilience

Storage runs across two servers with automatic failover. Each server uses hardware or software RAID.

## Data security

Network File Storage 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).

## Known limitations

The following constraints apply:

* Cluster size cannot be decreased after provisioning
* Minimum cluster size is 2 TiB
* 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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