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There are superblock, group descriptor table, inode bitmap, data bitmap , inode table ,etc. As I understood. these are stored in virtual memory sequentially.

  1. Are these metadata(superblock, group descriptor table, inode bitmap, data bitmap , inode table ,etc) of filesystem stored in SSD sequentially?
  2. Does a block in SSD , which contains pieces of file system, contains only filesystem data(metadata)?
  3. I know that if I repeatedly read the same physical address in SSD, atime(access time) of inode is updated. Is block in SSD, which contains atime, Garbage collected so that the data in the GCed block move to another free block. what i am saying is only read operation can cause GC.
  • if atime changes, then a read operation adds a write operation which might be or not be cached. If you want to increase duration of a frail SSD, you can disable partially or completely atime (relatime, lazytime, noatime). – A.B Jun 11 at 18:10
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    Please clarify what you want to know in question 3, it's not clear. – K7AAY Jun 11 at 18:48
  • I am only interested in physical address of SSD. If atime changes frequently due to repeatedly read operation, does it cause Gargbage Collection? I think it is not efficient for inode to move to other blocks because of only read operation. – YohanChoi Jun 12 at 3:57
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Since the SSD's programming, underneath the SATA or PCIe level, puts files wherever it wants to, the metadata you mentioned are not going to be in sequential order. A given block will not hold only metadata.

  • If it's underneath the PCIe layer, and that's as low as the kernel can go, wouldn't it be reasonable to say that as far as the OS use concerned it's sequential? – roaima Jun 11 at 20:07
  • Yet to be determined. – K7AAY Jun 11 at 20:09
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  1. "these are stored in virtual memory sequentially" not necessarily at all. They could be stored in completely separate structures, the memory locations of which are pretty much irrelevant.
  2. Since it's possible to store very small files content directly in the inode, it's not a reasonable assumption that a given block would contain only metadata.
  3. Sorry, no idea.
  • 2. if the metadata and data are stored in the same block, is it possible to corrupt metadata by reading adjacent data causing read disturb. – YohanChoi Jun 12 at 4:03

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