SSD manage read/write with bad blocks?

Rockman413

macrumors newbie
Original poster
Dec 2, 2014
26
0
Hi there,

How does SSD(all SSD, not just mac pro's) manage read/write with bad blocks? Will it automatically skip bad blocks and write to good blocks?

How about an SSD good block/sector has been written already, then that already-written sector turns bad, it will not be readable? Or it will still be readable, but you're going to get incomplete info/ corrupted file?
 

curmudgeonette

macrumors 6502a
Jan 28, 2016
505
325
California
How does SSD(all SSD, not just mac pro's) manage read/write with bad blocks? Will it automatically skip bad blocks and write to good blocks?
SSD's are always moving data around between blocks. This is necessary to level out the wear on blocks. SSD's are also over provisioned, i.e. they have extra blocks in case some fail.

How about an SSD good block/sector has been written already, then that already-written sector turns bad, it will not be readable? Or it will still be readable, but you're going to get incomplete info/ corrupted file?
If a block fails, then the data will be corrupted. Note though that blocks have extra space used to store error correcting codes. This allows the drive to correct a small error. Actually it is quite likely that many SSD blocks have some small defect which is covered over by the error correcting. If the defect becomes too bad, the drive can stop using that block, substituting an over provisioned block instead.
 

Rockman413

macrumors newbie
Original poster
Dec 2, 2014
26
0
so can I understand it in this way:



As long as I can copy the files out from whatever a bad SSD is , I can trust the files I copied is the same/good as original . Correct?



meaning if there's anything wrong with the file in a SDD, I can't copy to another computer that. All file I can copy is the same as original files.
 

h9826790

macrumors G5
Apr 3, 2014
12,770
5,579
Hong Kong
so can I understand it in this way:



As long as I can copy the files out from whatever a bad SSD is , I can trust the files I copied is the same/good as original . Correct?



meaning if there's anything wrong with the file in a SDD, I can't copy to another computer that. All file I can copy is the same as original files.
It’s hard to tell. OS, file system, firmware, all can affect the reliability of the data.

For normal use, may be your assumption is good enough. But technically I won’t say whenever you can read a file, that must be identical to the original.