![]() According to the NVMe Base Specification version 2.0, Data Units Written “contains the number of 512 byte data units the host has written to the controller as part of processing a User Data Out Command this value does not include metadata. For my previous article, I referred to Wikipedia’s account of those indicators, particularly indicator 07 Data Units Written, explained there as being the “number of 512-byte data units the host has written to the controller.” In the distant past, Apple has offered some models with internal SATA SSDs, but all more recent SSDs fitted by Apple are NVMe, which support a different set of SMART indicators. This article updates and extends that for Apple’s internal SSDs in particular. The program measures operation time.Last week I looked at how you can estimate the working life of an SSD using a measure of the total amount of data written to it, together with its TBW, the manufacturer’s estimate of the total that can be written to the SSD before failure is expected. Test ends in the middle of the testing area. The first block in the first pair will be Block 0, the second block in the first pair will be Block N (where N is number of last block for testing). Butterfly Read mode is similar to Read mode difference only in blocks' order.The program tests blocks one by one from minimum to maximum. The program sends the block of data to the drive and the drive writes the block (All previous data in the block on the drive will be overwritten with the pattern and cannot be recovered after that!) The program measures operation time for each block. In Erase mode the program prepares block of data field with special pattern and an LBA number.The program reads block of data into a temporary buffer and measures time of operation for each block. In Read mode device reads block of data and transfers it thorough interface to the host controller.The program measures operation time for each block. In Verify mode device reads block of data into drive's internal buffer only and checks for consistency, there is no data transfer through an interface connector/cable.Verify test may work in unreliable way on USB/Flash devices.Verify test may have restrictions on Block Size with 256, 16384 or 65536 sectors because of Windows limitations.Author wasn't able to get stable test results with two or more simultaneous tests. The program should not be run from a read-only device/media.Windows XP SP3, Windows Server 2003 (with restrictions), Windows Vista, Windows 7, Windows 8, Windows 10.Spindle start/stop function on ATA/SATA/USB/FireWire/SCSI HDD.Reporting defect information on SCSI HDD.Changing AAM, APM, PM parameters on ATA/SATA/USB/FireWire HDD.Reading and analyzing identity information from ATA/SATA/USB/FireWire/SCSI HDD.Temperature monitor for ATA/SATA/USB/FireWire/SCSI HDD.SMART tests running on ATA/SATA/USB/FireWire HDD.Reading and analyzing Log Pages from SCSI HDD.Reading and analyzing SMART parameters from ATA/SATA/USB/FireWire HDD.Reading in Butterfly mode (synthetic random read).Reading in linear mode – same as verification but also transfers data to the host.Verification in linear mode – fastest way to determine if your drive needs data rescue, has recoverable errors or in its perfect shape. ![]() USB Flash (pen drives) – surface tests only. ![]()
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