Since upgrading to 1.5.5 (from about 1.4.4), I have many new thumbnail directories in /media/hika_shop/uploads...
thumbnail_155x220
thumbnail_160x220
thumbnail_156x220
thumbnail_158x220
thumbnail_172x219
thumbnail_174x220
thumbnail_205x220
thumbnail_219x207
thumbnail_220x166
thumbnail_123x220
and on and on... one directory for every size of thumbnail that exists, I guess.
Is that okay? Was it done to avoid file handle limits when people change thumbnail sizes?
The images from thumbnail/ don't appear to be getting used... is it safe to delete them?
I found one broken image in the thumbanil_XXXxYYY directories. It was just data. Strings said GD library created it, so probably a bug in GD? I deleted it, and it regenerated fine.
So then I did:
file */*.jpg | grep -v JPEG and found one thumbnail that file thought was a minix v2 filesystem! Couldn't mount it, though (bad superblock) so am thinking that was a random wrinkle in the file's fabric. I deleted it, anyway.
The new version is phenomenal so far, especially in terms of the ease of upgrading.
Also, congrats on being now the top-rated Popular shopping cart on extensions.joomla.org. You deserve it!
-Henry