4K alignment of SSD drives

4K corresponds to 4096

HDD Mode:

First, let the SSD run in AHCI mode:

AHCI, the full name Advanced host controller Interface, which is the high-level hosting controllers interface, is more suitable for SSD SATA storage device communication protocols than the older "IDE" virtual mode. In AHCI and IDE mode, the SSD's performance gap percentage is around 65%. Therefore, it is recommended that SSD drives run in AHCI mode.

Software via as SSD benchmark. When AHCI is not turned on, the "Pciide-bad" similar warning word appears in the upper-left corner of the software interface. , the Open is "OK".

Two, hard disk three different modes of introduction:

1. RAID mode can be enabled via the hardware console, but trim is not supported for NCQ.
2, the IDE mode is a fixed score, support trim, boot start fast, does not support multi-channel optimization.
3, the AHCI mode can be understood to be, hardware conditions fully utilized when the state. Trim is supported when the driver is correct and supports NCQ.

iii. problems you may encounter after switching to disk mode:

Modifying the hard drive operation mode may cause the system to start a blue screen. The IDE switches to AHCI by first installing the AHCI driver, otherwise booting a blue screen. AHCI switches to the IDE for normal use.

Iv. methods for modifying from IDE mode to AHCI:

1. Click "Windows" key + "R" to go to the Run dialog box.
2. Enter "Regedit" to enter the registration form.
3, select the path "HKEY_LOCAL_MACHINE/SYSTEM/CURRENTCONTROLSET/SERVICES/MSAHCI".
4, the "Start" value changed to "0", the default is "3", restart the computer directly, in the "BIOS" to open the "AHCI" mode, normal access to the system.

4K Alignment:

One, 4K alignment detection and performance comparison:

4K is not aligned, the "bad" warning word is also indicated in the upper left corner of the as SSD benchmark software.

With 4K alignment and non-4K alignment, the SSD's performance gap percentage is around 53%.

Second, the principle of 4K alignment and the principle of traditional mechanical hard disk:

The read and write operation of the mechanical hard disk has always been in the sector, the size of each sector is 512 bytes, until recently, the size of the large capacity of the mechanical hard disk drive to 4096 bytes (we say 4KB), and the computer file system (FAT, NTFS, etc.), Always used to operate hard disks in 512-byte sector units.

While SSD read and write operation of different mechanical hard disk, SSD read and write the smallest unit called "page" (Common size of 4KB, depending on the specific particles), flash particles do not allow the same as a mechanical hard disk overwrite write. Therefore, to write new data where there is data, the erase operation is required, and the smallest unit of Erasure is the block (each block consists of a number of pages).

The traditional partition offset size is always starting from the 63rd sector of the disk (63X512B=31.5KB), so the first 4KB of user data must be stored between the 31.5kb~35.5kb of the system "logical sector", on the SSD, This causes all data to span between 2 pages, from the characteristics of the SSD above can be known, this situation will inevitably lead to SSD performance is severely affected (especially randomness), because each write operation on the SSD has become a read-erase-write operation.

Three, 4K alignment method:

1, users using the WIN7/WIN8/WIN10 system, as long as the use of the original system boot installation, the installation of the system with the partition tool partition will be self-aligning, do not require user intervention.

2, using the third-party partition software such as "Diskgenius" to manually specify the sector location, the partition when you select the "align to the following sectors integer times" The number of sectors select 8 or more, the online recommendation 2048, which is the value of the Win7 partition, the actual alignment size is 1024K. But it's a lot faster to test 4096. So I choose 4096 by default. It is important to note that XP does not support 4096.

SATA interface Native problem and performance comparison:

Comparison of one, 2.0 and 3.0:

SATA2.0 interface of the maximum theoretical speed only 300mb/s, and mainstream SSD read speed has broken 500mb/s, the SSD to SATA2.0 interface is undoubtedly a great performance waste. So we recommend that the SSD should be connected to the SATA3.0 interface of the theoretical transmission 6gb/s. However, the SATA3.0 interface is also divided into native SATA3.0 and third-party SATA3.0 interfaces.

SSDs are not recommended for use with interfaces provided by third-party chips, because third-party interfaces are restricted and affected more. The general Board specification will indicate which interface is native and which is a third party.

Second, third party SATA3.0 and native SATA3.0 interface difference:

Mvs91xx–ok, this column indicates that the SSD is not connected to the motherboard chip native interface, because mvs91xx represents the Marvell disk controller driver, the current motherboard of the third-party SATA chips are mostly used Marvell products.

Trim:

Win7 above the system default on trim, if not turned on, your SSD is not supported.

First, check whether trim is turned on:

1. Click the Start menu and enter "CMD" in the search field.
2. Right-click on the Search results icon and select Run with administrator privileges
3. Enter "fsutil behavior query Disabledeletenotify"
4. If the return value is 0, your trim is turned on
5. If the return value is 1, your trim is off

Note:

Reference http://diy.pconline.com.cn/329/3294218_all.html

4K alignment of SSD drives