Preface
Solid-kingdom difficult pressure If you have to use FTL to do the logical deal with and the bodily deal with among the conversion, if the SSD examine, write, delete and different everyday paintings withinside the case of unusual energy-down, may also motive mapping desk due to too overdue to replace and misplaced There is a fault that the SSD cannot be diagnosed with the aid of using the device.
At the equal time, which will enhance examine and write overall performance, normally use SDRAM to do the cache, if the system of analyzing and writing encountered unusual energy-down, SDRAM facts can be too overdue to put in writing Nand Flash facts loss, or replace the mapping desk too overdue to put in writing Nand Flash The mapping desk is missing.
Abnormal energy failure because of the phenomenon
SSD unusual energy failure normally there are 3 varieties of failure phenomenon:
1, SSD cannot reproduce the device identification:
They want to rebuild the mapping desk or with the aid of using easy and crude manner to re-manufacturing may be used;
2, normally after energy failure, SSD there are lots of “new horrific block”:
The mechanism at the back of the brand new horrific block is that once the SSD reads, writes, or erases unsuccessfully, it will likely be recognized as a horrific block. Of course, those blocks aren’t truly horrific, simply due to the fact they’re unusual Power failure because of the incorrect judgment.
3. SDRAM facts loss;
The common energy-down safety mechanism
Each energy-down safety mechanism to recognize special, special for the consumer, the safety mechanism is absolutely special, normally there could be the subsequent practices:
1, shop all of the facts in SDRAM
Abnormal energy-down, SDRAM all facts have to be completely written to Nand Flash, in general, SDRAM capability is about to 1000% of the quantity of SSD naked capability, for small capability SSD, SDRAM wants to put in writing Nand Flash facts Relatively small, thru the extraordinary capacitor or tantalum capacitor can keep to put in writing facts. However, if the SSD capacity is huge sufficient, for example, 8TB, then, SDRAM want to put in writing Nand Flash facts could be very huge, if nevertheless rely upon extraordinary capacitor or tantalum capacitor to do energy deliver, will necessarily face the subsequent 3 complex problems:
the want for greater tantalum capacitor debris to do the safety, withinside the real engineering practice, that is a totally severe check, the engineers face the thickness, the usual length limit, PCB location isn’t always sufficient to use;
b, even though there’s sufficient capacitance to do the safety, whilst the implementation of the “restart”, the SSD will now no longer begin properly, you have to first close down for a while earlier than restarting, due to the fact: SSD want to position all of the tantalum capacitors after energy Identified;
c, whilst using some years after the tantalum capacitor or extraordinary capacitor after aging, whilst the tantalum capacitor energy deliver cannot attain the preliminary layout goal value, the consumer nevertheless has facts loss after energy loss or SSD cannot perceive the ability risks, if the preliminary layout That is, to do redundant capacitors, then, will go back to the problem “b” loss of life cycle.
It is enjoyable that the troubles of b and c are the best answers to resolve those thorny troubles most effective want the engineer’s sufficient thoughts and enjoy most effective.
2, Most effective shop the SDRAM consumer facts, without saving the mapping desk
This will lessen using SDRAM and using tantalum capacitors, “do now no longer shop the mapping desk” does now no longer imply that the mapping desk is misplaced, simply do now no longer shop the remaining facts write replace the map, whilst the SSD re-energy, Looking for the remaining mapping desk to shop the brand new facts written to re-construct the mapping desk, the drawbacks of this technique isn’t always sufficient mechanism to set the reasonable, then rebuild the mapping desk could be longer, SSD takes a while to every day get right of entry to every day
For controllers without SDRAM layout, all facts are written immediately to Nand Flash. When facts are misplaced, the facts that aren’t always written to Nand Flash could be again to the host. If no extra facts wish to be saved, High-reliability necessities of the application, no SDRAM layout is king, its consultant is a German business logo master, its most effective disadvantage is that the overall performance isn’t always properly sufficient, in fact, many packages and the want for the best overall performance, and Is “sufficient” overall performance.
Test techniques and principles
Specific check, SSD want as a device disk and as a disk from the 2 instances of testing, so the principle disk and do from the disk check technique is the most effective distinction is that the principle disk want to check the laptop to energy off the machine, and from the disk, most effective SSD may be at the energy off.
a, respectively, of the SSD as a clean disc, facts are written withinside the 25% and 50% whilst writing facts, the write facts for 85% and 3000, respectively, the unusual energy down 100% check write facts, every down And the energy-on time c program language period of three seconds;
The precept of writing special capability facts to the disk is: When the SSD write a positive quantity of facts, the history started to rubbish series, the rubbish series approach that the relocation of facts, facts migration approach that the mapping desk updates, right now Abnormal energy failure is mostly a problem.
b, whilst every day write facts, the SSD unusual energy-down
c, whilst the facts is deleted whilst the unusual energy-down
In the windows, delete the facts additionally want to carry out 8 actions, and the established order of the equal document, the mapping desk additionally want to replace.
d, whilst the SSD examine record is unusual energy down, check 3000 times, energy off time c program language period of three seconds;
e, whilst the everyday shutdown system unusual energy down, check 3000 times;
f, whilst every day begin of the running device unusual energy down, check 3000 times;
