Quote:
Originally Posted by Toony
The original Card is a SanDisk 4GB Class 4 so it should only have about 6MB/s write, 17 MB/s read
I replaced it with a SanDisk 32GB Ultra Card that has 17MB/s write and about 36 MB/s read! I have the feeling that the Bookcovers in my collections load much faster now. |
One issue is that quite a few higher class cards have worse small block read/write performance than that measured for lower class cards. One horrible example is the Sony 32GB SD card I recently added to my digital SLR as the secondary card (used for RAW and video). It has excellent large block read/write speeds and sucks at the small block read/write testing using CrystalDiskMark. For my camera, this is fine since I'm writing megabytes at a time. For an ereader where you are reading and writing much smaller data blocks, not so fine.
You can do a search for more information on the issue. A couple of sites to check are:
SD Card performance round-up
SD Strange Results
And a link to some discussion on Mobileread in the Glo Memory Upgrade thread (start around post 16):
Memory Upgrade Guide
I got into the original discussion around SD card speed when I ran into the same issue as Swoozle in the second link -- SD card class ratings seemed to have little to do with performance in my specific setting with faster Class 10 cards turning in poorer performance than a Class 4 card.
On the other hand, Samsung and SanDisk in my limited testing were the two best at keeping small block performance numbers at decent levels. However you are likely to find that testing 4 cards with the same size and class rating by the same manufacturer can give very different results.