best block size for file systems on USB media ?

[Julian Stacey]

Hi usb at freebsd.org
Do USB flash memory sticks have cache ram ?  What are best file
system block sizes to write USB media (to maximise access speed) ?
Any URLS to RTFM welcome ;-)

I'm using mine to back up my personal tree of private data, (mail
& tech notes & sources etc, lots of smallish files), I'm using
/usr/ports/net/rdist6 to backup.

My biggest stick, a 2G Sandisk Cruzer micro (vendor 0x0781 product
0x5151) is awfully slow (much slower per Meg than other manufacturers
smaller sticks) (& other 2G Sandisk sticks bought in same purchase
from same vendor are also awfully slow on Win-XP, so maybe these
have less or no cache ram (if such things have cache at all ?) or
maybe they were a fraudulent batch without cache when they should
have had cache or ... ? ) Maybe some other sticks work on different
block size ? Maybe for many of my small files, the stick needs to
read a big block, before modifying a small chunk & writing back to
block ?

Block sizes was a question I'd meant to ask earlier, just for normal
sticks with a normal FreeBSD FS on there, now it's become even more
of an interest, using a BSD FS within an encrypted gbde partition
ref.  Read
http://www.freebsd.org/doc/en/books/handbook/disks-encrypting.html which
is slower still from encyption overhead (noticeable doing a reload
into new empty FS).

Some FS issues might be better discussed later on fs at freebsd.org,
but first, what's known about USB hardware block sizes please ?

Julian
--
Julian Stacey: BSDUnixLinux C Prog Admin SysEng Consult Munich www.berklix.com
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