tbone tbone at
Wed May 30 17:57:23 UTC 2007

MogileFS stores each file as a single file on the underlying filesystem, 
then replicates the files based on whatever replication policy you use.

Lamont Granquist wrote:
> Does MogileFS chunk storage like GoogleFS does?  One of the strengths 
> of GoogleFS's design is that it writes out storage in 64MB chunks on 
> the chunkserver.  If you've got thousands of little 10kB files they'll 
> get coalesced into 64MB chunk files.  When a fileserver needs to be 
> replicated the chunkfiles can be replicated which means you can stream 
> 64MB at a time.  A back of the envelope calculation of the total time 
> to stream 64MB is:
> 4 ms + 64 MB / 30 MBs ~= 2 seconds
> versus unchunked seeking every 10kB:
> 6553 * 4 ms + 64 MB / 30 MBs ~= 26 seconds
> So how does MogileFS do this?  If I fill up 2TB with 10kB blobs of 
> data under MogileFS how long does it take to get all that data off the 
> disk? Does it have to do a seek for every 10kB?
> !DSPAM:8,465dbaae65032627629951!

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