Principle of operation. We use fast SSDs to cache requests for slow, but significantly more capacious and inexpensive HDDs. In this mode, each access to the virtual machine's hard disk is checked for the presence in the cache, and if it exists in the cache it is returned from there and not read from the slow disk. If the data is not found in the cache, then they are read from the HDD disk and written to the cache.
Advantages of the HDD + SSD cache technology. The main advantage of HDD + SSD-cache technology is the amount of available disk space. Also servers using this technology are cheaper, which is important for hosting of startup projects, test servers and support services.
What we recommend to run on servers with HDD + SSD drives:
Principle of operation. SSD (Solid-state drive) is a drive in which, unlike conventional hard drives, there are no moving parts. For storage in the SSD uses flash memory. In simple words, this is a big flash drive.
Advantages of SSD technology. The main advantage of SSD-drives is the speed of operation. In contrast to a conventional hard disk, there is no time spent on positioning the read heads — data access speed increases. According to the tests, the read / write speed on SSD is several times higher than that of conventional HDD.
Who will benefit from VDS or VPS on SSD?
Principle of operation. NVM Express (NVMe, NVMHCI, Non-Volatile Memory Host Controller Interface Specification) is an updated version of the SSD-drive. It uses its own, designed from scratch, interaction protocol, and is connected via the PCI Express port.
Advantages of technology NVMe. Read-write with NVMe drives are 2-3 times faster than with conventional SSDs. The PCI Express bus does not limit the speed of the disk - this provides an increase in performance. In addition, on NVMe parallel operations are processed faster, more read-write operations are performed per second.
When to order a virtual server with NVMe disk?