[tahoe-dev] [tahoe-lafs] #964: List sizes for storage using base-2 sizes, not base-10

tahoe-lafs trac at allmydata.org
Mon Feb 22 23:41:01 UTC 2010

#964: List sizes for storage using base-2 sizes, not base-10
 Reporter:  USSJoin       |           Owner:           
     Type:  defect        |          Status:  new      
 Priority:  minor         |       Milestone:  undecided
Component:  code-storage  |         Version:  1.6.0    
 Keywords:  usability     |   Launchpad_bug:           

Comment(by warner):

 /me runs into the room waving his hands madly like a muppet. nooo!

 Please don't contribute to the confusion by printing "x GB" and silently
 using it to mean 2^30^. The entire non-computer world, the SI, and every
 dictionary on the planet knows that the metric G suffix means giga means
 10^9^. And while I find "GiB" pretty funny-looking, it is an unambiguous,
 learnable, and eventually-straightforward term that clearly means 2^30^.
 Let's not conflate the two. Sure, this helps the hard-drive manufacturers,
 but it's a terminology bugfix, not a conspiracy :).

 I'm -1 on having a config option for pretending GB=2^30^: someone looking
 the web page (and not at the config file) would be unable to learn the

 In places where we have evidence that people want both sorts of values, we
 should give them both sorts of values. For example, on the "Storage Server
 Status" page, we currently show abbreviated GB (10^9^) and unabbreviated

 Total disk space:       319.73 GB       (319728959488)
 Disk space used:        - 311.44 GB     (311444250624)

 My hope was that the "319728959488" would look enough like the "319.73" to
 cue the reader into remembering that GB means 10^9^, but the original
 poster's experience suggests this failed. Some other options for that

 Total disk space:       319.73 GB       (319728959488) (297.77 GiB)

 Total disk space:       319.73 GB(10^9) (319728959488)

 Total disk space:       319.73 GB(10^9) (319728959488) 297.77 GiB(2^30)

 Since this is a web page, we could also have a popup over the "319.73 GB"
 line that displays a number of other formats, not unlike we recently added
 popup to Foolscap's log-web-viewer display to show timestamps in alternate
 formats (UTC/local/short/long):

 319.73 GB (10^9)
 297.77 GiB (2^30)

 I'm -0 on having a config option that makes these pages display GiB
 '''instead''' of GB, as long as it never ever tries to pretend that GB is
 2^30^, and that there continues to be a full-number-of-bytes display so
 someone looking at the abbreviation has a chance to figure out what it
 and become confident in our consistent use of terms.

 > This is not a convincing argument, since you're more likely to need to
 > how many 1 MiB files, say, can be stored in a terabyte. (BTW, your mom's
 > estimate would be wildly wrong for 20-byte files due to overhead.)

 Huh? Except for programmer-driven test cases, I don't think there's any
 particular quantization on filesizes. I'm not counting 1 MB or 1 MiB
 I'm counting how many digital pictures I can stuff onto a disk, and
 all sorts of random sizes. The only real quantization I can think of would
 the chapters on a ripped DVD image (according to wikipedia these are
 1 GiB in size), but I really don't think "how many non-terminal DVD VOB
 can I fit on this disk" is a common question.

 > Hitherto I believe we've been using "GiB" to mean 2^30^ (per
 > http://en.wikipedia.org/wiki/Binary_prefix ) and we may have sometimes
 > using "GB" to mean 10^9^.

 We're '''always''' using GB to mean 10^9^ and GiB to mean 2^30^. I fix the
 code if I discover it doing otherwise.

Ticket URL: <http://allmydata.org/trac/tahoe/ticket/964#comment:7>
tahoe-lafs <http://allmydata.org>
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