> 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/block-storage/overview/limitations.md).

# Limitations

Volume size limits, performance thresholds, and operating system support constraints for IONOS CLOUD Block Storage.

The following are a few limitations that you can encounter while using Block Storage:

* We guarantee operation for the selected operating systems until the vendor or upstream support is available.
* Microsoft Windows Server versions are also supported until vendor support is available. For more information, see [<mark style="color:blue;">Prerequisites</mark>](/cloud/backup-and-storage/block-storage/overview/prerequisites.md).
* The following volume minimum and maximum values apply based on the storage type.

| **Storage Volume**                   | **Essential**                  | **Balanced**                                                            | **Performance**                                                         |
| ------------------------------------ | ------------------------------ | ----------------------------------------------------------------------- | ----------------------------------------------------------------------- |
| Minimum size per volume              | 1 GB                           | 1 GB                                                                    | 1 GB                                                                    |
| Maximum size per volume              | 4 TB                           | 4 TB                                                                    | 4 TB                                                                    |
| Maximum Read/write speed, sequential | 200 MB/s (static per instance) | 300 Mb/s per volume at 1 MB block size                                  | 600 Mb/s per volume at 1 MB block size                                  |
| Maximum Read speed, full random      | 1,100 (static per instance)    | 24,000 IOPS at 4 KB block size and minimum 2 Cores, 2 GB RAM per volume | 45,000 IOPS at 4 KB block size and minimum 4 Cores, 4 GB RAM per volume |
| Maximum Write speed, full random     | 1,100 (static per instance)    | 18,000 IOPS at 4 KB block size and minimum 2 Cores, 2 GB RAM per volume | 30,000 IOPS at 4 KB block size and minimum 4 Cores, 4 GB RAM per volume |

Larger volumes can be made available on request. For more information, contact [<mark style="color:blue;">IONOS CLOUD Support</mark>](https://docs.ionos.com/cloud/support/general-information/contact-information).


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