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--- systems:harddrive [2016/12/01 01:40] – superwizard
+++ systems:harddrive [2017/04/29 03:55] (current) – superwizard
@@ Line 1: / Line 1: @@
+====== Raid Reliability ======
+From: https://www.servethehome.com/raid-calculator/raid-reliability-calculator-simple-mttdl-model/
+<code>
+It took a lot of back and forth but the basic idea is this, the calculator is “directionally” correct
+but is not the most accurate way to model all of that stuff. We did evaluate a much faster model but on
+an AWS m1.small instance it was taking over 15 minutes to complete with only one user. Simply put, this
+RAID reliability calculator will give you a fairly good idea regarding which RAID level is the most
+reliable given a number of drives.
+</code>
+====== Fixing Disk Signature Collisions ======
+From: https://blogs.technet.microsoft.com/markrussinovich/2011/11/06/fixing-disk-signature-collisions/
+<code>
+Method 1: If you right-click on the disk, the utility offers an “Online” command that will cause
+Windows to analyze the disk’s partition table and mount its volumes:
+Method 2: With the disk signature in hand, open an administrative command prompt window and run
+Diskpart, the command-line disk management utility. Enter “select disk 2”, replacing “2” with
+the disk ID that the Disk Management utility shows for the disk. Now you’re ready for the final
+step, setting the disk signature to its original value with the command “uniqueid disk id=e9eb3aa5”,
+substituting the ID with the one you saw in the BCD:
+</code>
 ====== M.2 SSD ? HOW TO TELL WHICH IS WHICH ======
@@ Line 5: / Line 32: @@
 From: http://arstechnica.com/gadgets/2015/02/understanding-m-2-the-interface-that-will-speed-up-your-next-ssd/
-KEY	CARD MEASUREMENTS	INTERFACES	COMMON USES
+^KEY	^CARD MEASUREMENTS	^INTERFACES	^COMMON USES ^
-A	1630, 2230, 3030	PCIe x2, USB 2.0, I2C, DisplayPort x4	Wi-Fi/Bluetooth, cellular cards
+|A	|1630, 2230, 3030	|PCIe x2, USB 2.0, I2C, DisplayPort x4	|Wi-Fi/Bluetooth, cellular cards|
-B	3042, 2230, 2242, 2260, 2280, 22110	PCIe x2, SATA, USB 2.0, USB 3.0, audio, PCM, IUM, SSIC, I2C	SATA and PCIe x2 SSDs
+|B	|3042, 2230, 2242, 2260, 2280, 22110	|PCIe x2, SATA, USB 2.0, USB 3.0, audio, PCM, IUM, SSIC, I2C	|SATA and PCIe x2 SSDs|
-E	1630, 2230, 3030	PCIe x2, USB 2.0, I2C, SDIO, UART, PCM	Wi-Fi/Bluetooth, cellular cards
+|E	|1630, 2230, 3030	|PCIe x2, USB 2.0, I2C, SDIO, UART, PCM	|Wi-Fi/Bluetooth, cellular cards|
-M	2242, 2260, 2280, 22110	PCIe x4, SATA	PCIe x4 SSDs
+|M	|2242, 2260, 2280, 22110	|PCIe x4, SATA	|PCIe x4 SSDs|
+From: https://en.wikipedia.org/wiki/M.2
+<code>
+Legacy SATA - Used for SATA SSDs, and interfaced through the AHCI driver and legacy SATA 3.0
+PCI Express using AHCI - Used for PCI Express SSDs and interfaced through the AHCI driver
+AHCI has some inherent inefficiencies when applied to SSD devices, which behave much more
+like DRAM than like spinning media.
+PCI Express using NVMe
+At a high level, primary advantages of NVMe over AHCI relate to NVMe's ability to exploit
+parallelism in host hardware and software
+</code>
 <code>