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> Internal Cf Slot Speed?, how fast is it?
xamindar
post Jun 7 2010, 02:28 PM
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I am thinking about replacing my internal microdrive (again) with a compact flash card this time. Anyone know the maximum speed the zaurus can write on that interface? It might even be the same as the external interface in which case I can probably just test it myself before I reopen my Z. It would be pointless to install a card that can be written to at 40mb/s if the zaurus could only go at, for example, 4mb/s.

On a related note, ho can I test it? hdparm? What is the best way to test any cards actual speed?
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xamindar
post Jun 7 2010, 05:12 PM
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Looks like the cf slot can only go at a maximum of 2.30MB/sec based on hdparm tests. it reported 2.30MB/sec with both an old 128mb cf card and a class 4 SD card in a cf adapter. My Hitatchi 4GB microdrive comes back with 1.70MB/sec. The microdrives probably have better random access times though. Will using a high speed compact flash card help with random access times?
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utx
post Jun 8 2010, 01:46 AM
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QUOTE(xamindar @ Jun 8 2010, 03:12 AM) *
The microdrives probably have better random access times though. Will using a high speed compact flash card help with random access times?


Microdrives have better one random sector write perfomance (flash devices may need to manipulate with the whole eraseblock, which means about 64kB).

Flash should have better read performance, as it does not need to seek, and probably also continuous block write (modern flash devices are much faster than microdrives).

Note that you need to adjust file system parameters to work better on flash devices:

- async mount: Async mode buffers as many blocks as possible and then writes to the device. It allows to write the whole eraseblock in a single operation. Sync mode may cause up to 50 times slower operation of flash devices (depends on firmware of particular flash device).

- noatime: Atime (writing access time on each read) causes many small random writes. If you can live without atime support, your rotating storage devices may perform up to 2.5 times faster (depends on file sizes and seek time) and flash devices may perform many times faster. Note that latest 2.6.3x kernels write atime only once daily by default.

- If you can live with a bigger danger of damage after unexpected crash, you can experiment with commit=nseconds or use less secure journaling. (On fat systems, you can combine with flush option to get data sync on close operation.)
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