*Rani of Hearts-Reena Kapoor Paristan#55*The Cave Woman - Page 3

T(write) = T(position) + (D/R(peak))

R(effective) = D / T(write) = D / T(position) + (D/R(peak)) = F * R(peak)

D = R(effective) * T(write)

D = F / (1-F) * R(peak) * T(position)

80900

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cleaning the log - LFS

we expect the cleaner to read in M existing segments, compact their contents into N new segments (where N < M), and then write the N segments to disk in new locations. The old M segments are then freed and can be used by the file system for subsequent writes.

segment summary block : to determine whether a block is live or dead.

READ and LOOKUP - partially idempotent

WRITE - idempotent

GFS:

The master periodically communicates with each chunkserver in HeartBeat messages to give it instructions and collect its state

Clients interact with the master for metadata operations, but all data-bearing communication goes directly to the chunkservers

 a client asks the master which chunkservers it should contact

Virual File System:

The key idea is toabstract out that part of the file system that is common to all file systems and putthat code in a separate layer that calls the underlying concrete file systems to actually manage the data.

Congrats 

New AT 🥳

So kafi achi parhai ki Hai masu ne idhar😃

Good going😃

yes im gonna continue studying here only.. sorry replies baad me 

-no caching of data at client end

-master doesn't keep log of chunkservers having replicas

-order of append doesn't matter

-stale replicas -> replica chunks and master keeps updating version number -> if a chunk doesn't have updated number -> master detects it as stale 😲

-garbage collection -> hides files instead of deleting -> deletes them only if they arent reaccessed for 3 days

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