On 2015-06-18, Nick Holland <[email protected]> wrote: > The SSD has some number of spare storage blocks. When it finds a bad > block, it locks out the bad block and swaps in a good block. > > Curiously -- this is EXACTLY how modern "spinning rust" hard disks have > worked for about ... 20 years
Easily 25, for SCSI disks. > Now, in both cases, this is assuming the drive fails in the way you > expect -- that the "flaw" will be spotted on immediate read-after-write, > while the data is still in the disk's cache or buffer. There is more > than one way magnetic disks fail, there's more than one way SSDs fail. > People tend to hyperventilate over the one way and forget all the rest. They also tend to forget that magnetic disks also corrupt data, or never write it, or write it to the wrong place on disk. Time to remind people of this great paper: "An Analysis of Data Corruption in the Storage Stack" https://www.usenix.org/legacy/events/fast08/tech/full_papers/bairavasundaram/bairavasundaram_html/index.html If nothing else, read section "2.3 Corruption Classes". It should scare the bejesus out of you. -- Christian "naddy" Weisgerber [email protected]
