The relationship between SAS and SATA interfaces and HBA and Raid All disks behind the HBA are directly connected, and the performance only depends on the HBA itself. HBA+SAS expander will go through the middle of the expander, of course, there will be a delay, and the total bandwidth will be affected by the performance of the expander and the performance of the HBA.
(PRUnderground) September 13th, 2023
All disks behind the HBA are directly connected, and the performance only depends on the HBA itself.
HBA+SAS expander will go through the middle of the expander, of course, there will be a delay, and the total bandwidth will be affected by the performance of the expander and the performance of the HBA.
SAS expander is also a SAS device, and it also has firmware. Of course, there will be compatibility issues with HBA/RAID and hard disks, and it is also divided into types. SAS expander is rarely used in personal assembly.
A mini SAS interface has 4 SAS ports, each of which is 6Gbps; only to save space, it is made into an SFF-8087 mini SAS x4 interface.
U.2 is a 2.5-inch SSD interface, originally called SFF-8639.
The end of the motherboard is the mini SAS (SFF-8643) interface.
The expander is used to expand the bay. It can be in the form of a card or integrated into the backplane of the hard disk of the chassis. It can be simply understood as a device that expands 1 MINISAS port into more than 4 miniSAS ports (more than 16 miniSAS ports). Hard disks, up to 128), expander cannot operate independently, and at least one storage controller (HBA or RAID card) needs to be connected.
HBA can be understood as a storage controller based on the PCIE bus, which can run in IT mode (the system directly recognizes the hard disk) or IR mode (hardware raid, RAID0/1 is more common and also supports JBOD and other modes) Some HBA cards can be flashed by firmware. way to switch between IT/IR modes.
HBA card = fool network card
RAID Card = Advanced Network Card
SAS expansion card = Alias of Expander
Expander is talking about a chip, which can be integrated on the backplane, or it may be a separate card (non-array card); the array card is used for RAID; the HBA card is a pure expansion (some array cards can be flashed IT mode is used for HBA); the array card/HBA card generally only has 4-8 interfaces (two MINISAS are divided into four)
The SFF-8087 Mini-SAS connector is designed for implementing Mini SAS internal interconnect solutions.
The SFF-8087 is a 36-pin “Mini SAS” connector with a plastic locking interface compatible with internal connections. A typical application is a SAS link between a SAS HBA and a SAS drive subsystem.
SFF-8087 complies with the latest 6Gb/s Mini-SAS 2.0 specification and supports 6Gb/s data transfer protocol.
The Mini-SAS external counterpart of the SFF-8087 is the SFF-8088, which is also compatible with Mini-SAS 2.0 and supports 6Gb/s SAS data transfer speed.
Both the SFF-8087 and SFF-8088 support up to 4 ports (4 lanes) of SAS data.
SFF-8643 is the latest HD MiniSAS connector design for implementing HD SAS internal interconnect solutions.
The SFF-8643 is a 36-pin “High-Density SAS” connector with a plastic body normally used for internal connections. The typical application is an INTERNAL SAS link between SAS HBA and SAS drives.
SFF-8643 complies with the latest SAS 3.0 specification and supports 12Gb/s data transfer protocol.
The HD MiniSAS external counterpart of the SFF-8643 is the SFF-8644, which is also SAS 3.0 compatible and also supports 12Gb/s SAS data transfer speed.
Both the SFF-8643 and SFF-8644 can support up to 4 ports (4 lanes) of SAS data.
SATA expansion card has several ports, it is just a few ports
The SAS HBA card expands the standard SAS, which can be connected to the SAS Expander
Expander is talking about a chip, which can be integrated on the backplane, or it may be a separate card (non-array card); the array card is used for RAID; the HBA card is a pure expansion (some array cards can be flashed IT mode is used for HBA); the array card/HBA card generally only has 4-8 interfaces (two MINISAS are divided into four).
The expander can be thought of as an additional function (either a chip or a separately integrated card) that provides the following functions: allowing the backplane to support dual ports (sas exclusive such as 6gb/s to 12gb/s), cascading and faults Transfer (failover) This requires dual HBA support. For example, the common backplane is divided into mother and daughter parts. One HBA card is called A, M, and D cards, and the other HBA card is called B, and M and D cards are connected. Therefore, in normal use, 2 cards can be shared separately. One of the bandwidth problems, the other is fully responsible).
Compared with the Raid card, the HBA card can provide the hard Raid function because of the on-board cache and chip. This can be understood as an offline (offline) function to reduce the burden of the main CPU.
The HBA has no onboard cache and the chip only provides PCIe channels (that is, enough bandwidth) to the HDD, so it can only use soft raid (recommended ZFS as the bottom layer) and then if you consider adding NVMe disks later, it is recommended to HBA, Raid card I/O cpu cannot Well driven NVMe Raid.
Then your solution must include one HBA or Raid card. It should be noted that the chassis must be equipped with a Mini SAS HD Ext-to-Int adapter (this thing plays the role of external to internal). With this thing, your HBA is plugged into the host and the external SFF cable is connected to the adapter (the small thing is on the chassis/external hard disk cabinet), and then the adapter is wired to connect to the backplane.
Host Bus Adapter, HBA for short, includes array cards and fiber optic cards, but the server field generally refers to Fibre Channel cards (FC and FCOE); and expansion cards are only used for home motherboard SATA port expansion, which can be easily assembled. raid, most of the server array cards also support SAS hard disk, advanced raid function, and faster 12Gbps rate.
The concept of “port” and “connector”. The port of a hardware device is also called an interface, and its electrical signals are defined by the interface specification, and the number depends on the design of the control chip (Controller IC, also including RoC). But whether it is an interface or a port, it must rely on the representation of an entity- mainly pins and connectors, in order to play the role of connection and then form a data path. Therefore, there is an interface connector. , they are always used in pairs: one on the hard drive, HBA, RAID card, or backplane “snap” together with the other on the cable end. As for which side is the “receptacle connector”, socket connector), which side is the “plug” (plug connector, plug connector), depending on the specific connector specification.
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