saving struct array is slow and returns an error message

i have a small struct array that when i try to save returns

Error using save
Error closing file
/Users/fchang/Dropbox/Public/smalldataset/fcProcessedStorage/201601-test-adf/s1/[fcSpotDetection]/spotMLEs/spotMLEs(BWY819-14_w2-FITC(WhiteTTL)_s1_t1).mat.

when i use try /catch around the save, there is no error message, and the file is successfully saved. first of all, it takes a long time, and second why is there an error message? i tried several save version flags and it does not matter for both problems.

linked is the workspace save (that also returns the error message but file is saved anyways)

workspace

spotMLEstructArray =

13x1 struct array with fields:

    data
    theta0
    readNoise
    domains
    type
    thetaMLE
    thetaVar
    lambdaModel
    maxThetas
    gradFunc
    hessFunc
    logLike

K>> whos spotMLEstructArray Name Size Bytes Class Attributes

spotMLEstructArray      13x1             67592  struct

Answer 1

[Walter Roberson]

Saving to networked files is often slow. If you have enough disk space it is usually faster to save to local disk and then to copy the saved .mat to the networked disk. For example,

tfile = [ tempname() '.mat' ];
destfile = '/Users/fchang/Dropbox/Public/smalldataset/fcProcessedStorage/201601-test-adf/s1/[fcSpotDetection]/spotMLEs/spotMLEs(BWY819-14_w2-FITC(WhiteTTL)_s1_t1).mat';

save(tfile, 'variable1', 'variable2', ...)
system( sprintf('mv "%s" "%s"', tfile, destfile) );

[Frederick Chang]

note that the dropbox folder is on the local drive (ssd), so the slowness of the save function is not limited by this. just to make sure, i also tried saving to my desktop (local drive, ssd) and it is slow + reports same error

also note that the variable being saved, the struct array, is relatively small, so size of the data being saved is not a factor.