This installs the generic AHCI Microsoft driver and it is really a poor driver for your hardware and you will need the Intel ones to get full performance. It says to use this Driver 'Intel® 631xESB/6321ESB Ultra ATA Storage Controller - 2680' Which Im not able to install.
Even in this age of SSDs, we're still working with technologies that were developed in the last century. These...
include Advanced Host Controller Interface and redundant arrays of independent disks.
AHCI and RAID are often viewed in the same context, but they serve different purposes. Whether you're operating a single PC or a full storage environment, understanding the AHCI vs. RAID question is important. Each includes a different set of capabilities that can help ensure smooth operation of your storage environment. This article lays out the basics to help you make the right decisions when it comes to AHCI vs. RAID.
AHCI vs. RAID fundamentals
AHCI is the standard for the storage interface that lets software -- typically an OS -- communicate with SATA devices. Intel introduced AHCI in 2004 as a replacement for the aging Parallel ATA/Integrated Drive Electronics interface.
AHCI has enabled some of the capabilities inherent in SATA devices to actually be used on the OS side. For instance, SATA enabled support for hot swapping devices -- the ability to plug a new device in to a computer without having to reboot the computer. AHCI enables Windows, Unix and Linux OSes to use hot swapping.
Native Command Queuing (NCQ) on hard drives is a prominent feature introduced in SATA on the hardware side and AHCI on the OS side. Rather than operating on a traditional serial command queuing, first-in, first-out command execution process, NCQ lets disks -- including SSDs -- optimize how they handle simultaneous storage operations. The benefits are different depending on the type of storage in use. For hard drives, NCQ means that the read and write heads have to move less often. Read and write head movement is one of the biggest contributors to latency in HDDs, and optimizing their movement yields performance gains.
AHCI also provides benefits for SSDs, such as improved support for large file transfers, but its shallow queue depth limits the number of I/O requests that can be serviced. Workarounds are needed to enable SSDs to avoid command queuing, which can slow things down. Even with NCQ, the need to queue commands at all implies that there's a holdup somewhere that requires a queue to be formed.
To address the queuing issue permanently, the nonvolatile memory express (NVMe) standard has been developed to replace older interfaces, such as SATA, and introduce new command management capabilities. NVMe is designed for flash, eliminating the downsides that come from supporting modern storage media with old protocols.
Where RAID fits in
RAID was first used in 1987. Today, RAID is far more capable than early versions and is beginning to be supplanted by newer technologies, such as erasure coding.
Scott Sinclair, senior analyst at Enterprise Strategy Group, discusses RAID and erasure coding.
RAID is a data protection and availability mechanism that lets a system continue to operate after the loss of one or more HDDs or SSDs. It typically includes the ability to rebuild the contents of a failed disk once it has been replaced.
RAID storage volumes can be created on any computer with multiple storage devices as long as the computer or storage array supports RAID. Some PCs may not support a RAID option, and some storage arrays, known as JBODs (just a bunch of disks), don't support RAID.
On modern PCs, enabling RAID on SATA ports on the motherboard usually also enables AHCI support. Having RAID enabled lets you do the following:
- install multiple storage devices -- hard drives and SSDs -- and use them as a single volume;
- enable redundancy by supporting the loss of a device; and
- improve performance by spreading storage operations across multiple devices rather than a single disk.
You need at least two disks as a part of a RAID group. Two disks enable mirroring, or RAID 1, which means that, anytime data is written to one disk, the controller copies that write to the second disk. Alternatively, you can use striping, or RAID 0, to instruct the computer to write data to both disks simultaneously. Mirroring writes can cause performance degradation, although your storage will remain available if one of the disks fails. Striping can improve both read and write performance because there is twice the performance capacity to be had.
There are other RAID levels, with the most common being RAID 5 and RAID 6. Both use parity to help protect data from device failure. With RAID 5, a system can withstand the loss of a single disk, and with RAID 6, two disks can bite the dust and still be operational.
Bottom line on AHCI vs. RAID
![Install osx86 without ahci vs atascocita Install osx86 without ahci vs atascocita](http://images-thumbs.thefullwiki.org/M/i/n/Minicomputer.png)
In discussing AHCI vs. RAID, it's important to know where these two concepts fit into the overall storage environment. AHCI ensures full functionality in SATA devices. RAID provides mirroring and striping capabilities that are key to data protection.
Getting these fundamentals right is critical to maintaining a fully functional storage environment.
this post is a continue to the 'Prepare the disk partitions' post,
this post cover BIOS options that you need to try and play with in order to get the installation running, the installed system to boot and allow the leopard work smoothly.
*****for newbies*****
todays all PC computers have a BIOS (Basic Input Output System), it is a CMOS chip saving both configurable data and permanent data and a small code part needed to boot the machine and handle hardware initialization commands.
BIOS have a setup screen that allows you to specify the configuration you prefer for the system. the bios screen can be accessed in many different ways depending on the computer. some machines use 'del' button, when the computer loads, just press delete and the BIOS appears, some use F2 or F12 all depends on the type of bios installed on your machine ('American MegaTrends' or 'Award Software' or 'Phoenix Technologies' etc.), in the first screen you see when the PC powers up there should be a message saying how to enter setup/bios.
this should be the first thing to set in the bios, it is the most important part if you decided to use vanilla kernel, the thing is that intel created a virus/warm protection in the CPU level (some sort of security feature), since warm and virus infect the computer by copying their execution instructions to a buffer, the CPU allows the OS to mark what areas in the memory are for data usage only and if someone tries to execute code from those areas the CPU wont allow it, that is why you can set the CPU to activate its 'No Execution' (NX on AMD CPU) protection or 'Execute Disable' (XD on intel CPU) protection. probably leopard decided to support it fully, and not load if this option is not enabled in order to provide a safer OS, and probably that is why if this parameter is set to false or disabled the system will loop reboot forever until the parameter is set back to enable.
set the 'Execute Disable Function' to Enabled
sometimes it is called XD (eXecution Disabled) and looks like this:
During runtime the OS ask the CPU for information regarding different areas, each query is done using a hex value set to a CPU register, not all CPU supports all features this is why at boot time the OS check what are the supported features, each CPU gives different answers to a given value depending on the number of features it support, and in this way it determines what CPU it is running on, but older OS such as NT, 95, 98, Jaguar, Panther etc. don't know of the new feature that new CPU has, that is why this BIOS parameter exist, it tells the CPU to act as if it is limited in the number of features it support for the sake of older OS, in our case leopard support all the CPU query features (leafs), that is why we need to set this parameter to disable and to allow the CPU to return its true values and to be able to identify the CPU for its true type.
set the Max CPUID Value Limit to Disabled
latest CPUs support internal thermal sensors and the CPU track the temperature, if it reaches a high or too low threshold counter measures are taken, such as: lowering voltage and speed of CPU (so less heat is generated) allowing CPU to cool down, sometimes when temperatures are critical the CPU is allowed to freeze all work or shutdown the computer as precaution measures (depending on the BIOS setup). this parameter can be set to enabled or disabled since today the hackintosh scene cannot support the thermal control from leopard (for all PCs), and as part of the installation you are asked to remove the kext (kernel extension) responsible for it, so you may enable it, i prefer to disable it and if everything is working well you can return and enable it back on to enabled value, if you don't have disabled (like me) Auto value will do just fine.
set CPU Internal Thermal Control to Disabled or Auto
ACPI 2.0 Support(Advanced Configuration and Power Interface)
ACPI is a standard that allow the OS to control the power management of hardware components, the BIOS feature only enable or disable the interface not the OS feature, that means that if the BIOS parameter is enabled then the OS can use (or not) the ACPI interface to control board and peripherals power supply, but if this feature is disabled then even if the OS will try to use the interface and activate components power it cannot do it (hence the word 'Support' in the title), and when leopard tries to control the power of the computer components and the ACPI is not available the result is eather leopard wont load or crash during runtime.another parameter that needs to be set is the: ACPI APIC Support and it should be set to enabled for the same reasons.
set ACPI 2.0 Support to yes
set ACPI APIC Support to enable
Core Multi-Proccessing
this BIOS feature is very simple yet very important, it allows Core 2 Duo CPUs to turn into Core 2 Solo, meaning the CPU will use only one of its cores, after hackintosh install if you experience a reboot loop (without the ability to reach single mode even) then try disable this option, otherwise use enabled.
set Core Mutil-Proccessing disable (if all goes well set enabled)
in this BIOS option you can set the standard your hard driver controller support,
it can support: IDE for legacy drives, SATA for new driver and RAID if available in your PC system, make sure these option set comply with your hardware setup.
if you use SATA then choose the AHCI option if you use IDE choose the ATA/IDE Mode: Legacy.
S.M.A.R.T option should be enabled unless you receive a S.M.A.R.T. error during DVD boot time, in that case disable it.
for SATA:
set Configure SATA as: AHCI
set ATA/IDE Mode: Legacy
set Configure SATA as: IDE
set S.M.A.R.T: Disabled
set Configure SATA as: IDE
set S.M.A.R.T: Disabled
thats it, next step is the installation process it self refer to 'Install Tiger' or 'Install Leopard' posts.
Enjoy.