Hi everyone,

 

I am running PreClear on newly added drives. They're unassigned drives.

 

The good thing about PreClear besides testing premature failures is that there are 3 steps to it. Pre-Read, Write Zeros and Read.

The information about the disk being cleared is being written to signature by (Unassigned Devices plugin?) in Unraid and Unraid won't do the clear once again, when disk will be added to the array. 

Also, any found bad sectors should be marked to SMART.

 

My question is: Will the information in the disk' signature about preclear already being done (and maybe even info about bad sectors) be lost when changing file system?

Should I do have set file system prior to preclear?

 

Many thanks for enlightening me. 

Edited September 13, 20241 yr by Digital Shamans

6 hours ago, Digital Shamans said:

My question is: Will the information in the disk' signature about preclear already being done (and maybe even info about bad sectors) be lost when changing file system?

No

10 hours ago, Digital Shamans said:

Unraid won't do the clear once again, when disk will be added to the array. 

As long as NOTHING is changed on the disk, that is true. If you format the disk BEFORE you add it to the array, the clear status is gone, and Unraid will need to clear it again before adding it.

 

Your question about file systems made me think I needed to clarify.

10 hours ago, Digital Shamans said:

Should I do have set file system prior to preclear?

Clearing removes all file system information.

 

Formatting to add a filesystem must happen after the drive is fully added to the array, so the format can be included in parity.

Indeed, a format removes file systems.
I should have added the disks to the array first then. It's a lesson to remember. 

 

Thank you guys!

18 minutes ago, Digital Shamans said:

format removes file systems

format creates a blank file system

The file system (even totally empty) takes up space on the drive.

 

Think of the hard drive as a room that can hold paper files. If you just toss all the papers on the floor, it would be a bear to find any specific paper. The file system is all the filing cabinets, the folders inside, the card catalog with all the cross reference information to locate any specific piece of paper.

 

Different file systems use different arrangements to keep track of the files, some file systems specialize in speed of access, others on file integrity, etc.

 

When you format a drive, it sets up all the structures needed to manage and index the files. That takes up a non-insignificant amount of room on the drive, before any files are even written.

 

Clearing removes ALL that information.

 

Parity emulates raw bits, it has no idea what files are, what file system you formatted, or anything.

I like the analogy!

When you say blank file system after format, do you mean the state of drive in which directories or/and file paths are still there, but no files themselves?

While cleared (zeroed?) disk has no file system whatsoever. 

I wonder what is the most fundamental structure of the file system in this context. Would that be empty directories or something else?

1 hour ago, Digital Shamans said:

When you say blank file system after format, do you mean the state of drive in which directories or/and file paths are still there, but no files themselves?

Yes, format (or file deletion) simply amends the table of contents to show the space is available for new files or directories. The raw bits that are files are still there, and file recovery software can make an attempt to sort through the mess and see if it can find anything sensible.

 

1 hour ago, Digital Shamans said:

I like the analogy!

To extend the analogy, formatting a drive dumps the contents of the folders on the floor. All the papers are still there, but good luck picking through them to find any specific one, let alone figuring out if you have all the papers that belong to any given file. There would be clues, like all movie files start with the name of the file and encoding type, but all the rest of the pages would look like random garbage.