Preface
Strong-state tough generate If you ought to use FTL to do the rational handle and the physical address between the conversion, if the SSD browse, write, delete and other normal perform in the scenario of irregular electricity-down, may well lead to mapping desk since of way too late to update and shed There is a fault that the SSD can not be identified by the process.
At the identical time, in order to make improvements to read through and generate general performance, generally use SDRAM to do the cache, if the course of action of examining and composing encountered abnormal ability-down, SDRAM data may perhaps be way too late to produce Nand Flash info loss, or update the mapping desk too late to produce Nand Flash The mapping table is missing.
Irregular power failure brought on by the phenomenon
SSD abnormal ability failure normally there are 3 kinds of failure phenomenon:
1, SSD can not reproduce the method identification, the will need to rebuild the mapping desk or by simple and crude way to re-creation can be utilized
2, numerous times after electrical power failure, SSD there are a large amount of “new bad block”
The system powering the new negative block is that when the SSD reads, writes, or erases unsuccessfully, it will be recognized as a bad block. Of study course, these blocks are not seriously undesirable blocks, just simply because they are irregular Electrical power failure brought about by the wrong judgment.
3, SDRAM info decline
Typical energy-down security system
Every power-down security mechanism to understand distinct, distinctive for the user, the protection system is fully diverse, usually there will be the following two methods:
1, preserve all the knowledge in SDRAM
Abnormal electrical power-down, SDRAM all knowledge should be totally prepared to Nand Flash, in standard, SDRAM ability is established to 1000% of the volume of SSD bare potential, for little capability SSD, SDRAM have to have to generate Nand Flash information Relatively small, by the super capacitor or tantalum capacitor can go on to publish knowledge. Nonetheless, if the SSD capability is huge enough, for case in point: 8TB, then, SDRAM require to write Nand Flash details will be incredibly significant, if nevertheless depend on tremendous capacitor or tantalum capacitor to do ability provide, will inevitably encounter the subsequent 3 challenging issue:
a, the require for far more tantalum capacitor particles to do the defense, in the actual engineering practice, this is a incredibly severe check, the engineers deal with the thickness, the standard size restrict, PCB region is not adequate to use
b, even if there is adequate capacitance to do the security, when the implementation of the “restart”, the SSD will not start off properly, you ought to very first shut down for some time ahead of restarting, mainly because: SSD need to set all the tantalum capacitor immediately after electric power Identified
c, when the use of a handful of decades soon after the tantalum capacitor or tremendous capacitor soon after growing older, when the tantalum capacitor electrical power provide can not achieve the preliminary design and style target worth, the person even now has details loss after power loss or SSD can not identify the possible threats, if the first design and style That is, to do redundant capacitors, then, will return to the trouble “b” death cycle.
It is gratifying that the complications of b and c are best answers to address these thorny complications only need the engineers sufficient mind and encounter only.
2, only help save the SDRAM user facts, with out saving the mapping table
This will minimize the use of SDRAM and the use of tantalum capacitors, “do not help save the mapping desk” does not signify that the mapping table is misplaced, just do not preserve the very last facts create update map, when the SSD re-power, Hunting for the final mapping desk to help you save the new knowledge prepared to re-make the mapping table, the downsides of this tactic is not ample system to established the fair, then rebuild the mapping table will be lengthier, SSD takes some time to typical entry to typical
For controllers without having SDRAM layout, all data is written specifically to Nand Flash. When information is dropped, the details that is not prepared to Nand Flash will be returned to the host. If no further details needs to be saved, Substantial reliability requirements of the software, no SDRAM structure is king, its agent is a German industrial model learn, its only drawback is that the general performance is not fantastic adequate, in fact, quite a few apps and the require for the greatest effectiveness, and Is “ample” general performance.
Exam approaches and concepts
Distinct exam, SSD will need as a program disk and as a disk from the two circumstances of tests, so the key disk and do from the disk examination strategy is the only variance is that the key disk have to have to take a look at the personal computer to energy off the device, and from the disk only SSD can be on the electric power off.
a, respectively, of the SSD as a blank disc, information is penned in the 25% and 50% when creating info, the generate knowledge for 85% and 3000, respectively, the abnormal energy down 100% check produce data, each and every down And the power-on time interval of 3 seconds
The principle of crafting different potential info to the disk is: When the SSD compose a sure amount of money of information, the track record began to rubbish assortment, garbage assortment means that the relocation of knowledge, details migration indicates that the mapping table updates, at this time Irregular energy failure is usually a issue.
b, when the regular write data, the SSD irregular electric power-down
c, when the info is deleted when the abnormal energy-down
In the windows, delete the info also need to accomplish 8 actions, and the establishment of the exact doc, the mapping desk also need to update.
d, when the SSD browse file is abnormal electrical power down, take a look at 3000 periods, electric power off time interval of 3 seconds
e, when the typical shutdown system abnormal electric power down, examination 3000 moments
f, when the normal commence of the functioning system irregular ability down, test 3000 moments