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The first HDD [11] had an average seek time of about 600 ms. [12] and by the middle 1970s, HDDs were available with seek times of about 25 ms. [13]Some early PC drives used a stepper motor to move the heads, and as a result had seek times as slow as 80–120 ms, but this was quickly improved by voice coil type actuation in the 1980s, reducing seek times to around 20 ms.
Many device interfaces or protocols (e.g., SATA, USB, SAS, PCIe) are used both inside many-device boxes, such as a PC, and one-device-boxes, such as a hard drive enclosure. Accordingly, this page lists both the internal ribbon and external communications cable standards together in one sortable table.
SATA 3 Gbit/s Intel's data sheet [13] claims 6,600/8,600 IOPS (80 GB/160 GB version) and 35,000 IOPS for random 4 KB writes and reads, respectively. Intel X25-E (SLC) SSD ~5,000 IOPS [14] SATA 3 Gbit/s Intel's data sheet [15] claims 3,300 IOPS and 35,000 IOPS for writes and reads, respectively. 5,000 IOPS are measured for a mix. Intel X25-E G1 ...
NVM Express over Fabrics (NVMe-oF) is the concept of using a transport protocol over a network to connect remote NVMe devices, contrary to regular NVMe where physical NVMe devices are connected to a PCIe bus either directly or over a PCIe switch to a PCIe bus.
NVM Express (NVMe): A modern interface designed specifically for SSDs, NVMe takes full advantage of the parallelism in SSDs, providing significantly lower latency and higher throughput than AHCI. [97] An M.2 (2242) solid-state-drive (SSD) connected into USB 3.0 adapter and connected to computer Mushkin Ventura, A USB that has an SSD inside
When enabled via the AHCI controller, this allows the SATA host bus adapter to enter a low-power state during periods of inactivity, thus saving energy. The drawback to this is increased periodic latency as the drive must be re-activated and brought back on-line before it can be used, and this will often appear as a delay to the end-user.
With so many ways to connect a hard drive (SCSI, Fibre Channel, ATA, SATA, SAS, SSA, NVMe and so on), it is difficult to predict whether S.M.A.R.T. reports will function correctly in a given system. Even with a hard drive and interface that implements the specification, the computer's operating system may not see the S.M.A.R.T. information ...
The SAS is a new generation serial communication protocol for devices designed to allow for much higher speed data transfers and is compatible with SATA. SAS uses a mechanically identical data and power connector to standard 3.5-inch SATA1/SATA2 HDDs, and many server-oriented SAS RAID controllers are also capable of addressing SATA hard drives.