CARDSPEED - Card Readers and Memory Cards

SanDisk Extreme IV 4GB SDCFX4-4096

For general information and other test results, see the overview  UDMA CompactFlash Cards .

The SanDisk Extreme IV CF are labeled as "Read/Write 40MB/s", where SanDisk calculates 1MB as one million bytes. At the same time, the box states that for the 266X speed, 1X would be 150KB/s. This is only true if 1KB is interpreted as 1024 bytes, as some older sources which suggest 1K = 1024 instead of 1k = 1000. The base for the 1X speed rating is the transfer rate of CD-ROM Mode 1 with 75 blocks of 2048 user bytes per second, giving 153,600 bytes per second. But that's a different story...

Specifications

Test Results		Read			Write
FireWire CF Reader		40.08MB/s	273x		36.86MB/s	251x
CF SATA Adapter		39.88MB/s	272x		38.97MB/s	266x

CF FireWire Reader

2007-05-02: First tests with the FireWire readers showed good read results, but the write performance stayed well below the claimed rate. In the meantime I found a CF to SATA adapter where the card showed good results. But now I finally found out how to get proper write results with this card using the FireWire readers.

The test setup:
SanDisk Extreme IV CF 4GB, SDCFX4-4096-902
Hama 55352 CF FireWire reader, Oxford FW 912 controller
TI TSB82AA2/TSB81BA3 FireWire, TI OHCI 1394 Driver
Read/Write directly from/to the media, no filesystem involved
Read/Write rates taken with a sample size of 4MB, 980 samples

The test showed an average trasfer rate of 40.08MB/s (273x) read and 36.86MB/s (251x) write.

CF to SATA Adapter

The test setup:
SanDisk Extreme IV CF 4GB, SDCFX4-4096-902
CF to SATA adapter with Marvell 88SA8040-TBC1 controller
ICH6R SATA Host
Read/Write directly from/to the media, no filesystem involved
Read/Write rates taken with a sample size of 4MB, 980 samples

The test showed an average rate of 39.88MB/s (272x) read and 38.97MB/s (266x) write.

Special Tests

More information will follow, see the  Explanations for the Special Tests  for details regarding the test procedure.