On Thursday 21 July 2005 17:58, Kristian Kielhofner wrote:
> > They are not the fastest - running hdparm -tT on them reveals a speed of
> > 2Mb/s which is about a third of the speed of 100Mbits ethernet. For call
> > recording I usually add an IDE hard drive and make sure that most
> > filesystems (e.g. /var,/tmp..) are loaded into a RAM disk
> >
> > Paul Hewlett
>
> Paul,
>
> SanDisk CF cards are often considered to be the best around. What
> problems were you having?
Horrible seek errors on boot up - eventually it would boot. Eventually it
would fail completely.
I currently use SuSE9.2 and there is a section on boot where it creates
devices 'Creating Devices'. Some makes display a continuous message on the
console viz :
hdc: hdc1 hdc2
If you are lucky the the flash is eventually recognised after 30-40 of these
messages - if unlucky it goes on indefinitely. SanDisk, Kingston Technology
and one other (who I forget) did this.
Also I have lost 2 flash completely - one was due to a power failure at the
customer (he also lost a RAIDED server) and one due to the cooling fan on the
CPU failing and the CPU cutting out on overheat.
>
> CF is both slow and fast. Seek times are very low, but sustained data
> transfer rates are not very good (ESPECIALLY for writes). 2Mb/s is
> actually more like 1/4 - 1/5 the speed of 100mbps ethernet...
Using ftp on a 100Mbytes network reveals a speed of 6.8Mb/s which is why I
made that comparison - its not a perfect comparison but benchmarking is not
an exact science..
Flash disks are actually sequential devices - the onboard firmware always
writes back to the next sector available and marks it as that sector number -
there is a nice doc on the SanDisk site that describe the process. Flash has
a limited number of write cycles and this way they spread write counts evenly
amongst all sectors on the Flash.
Paul
--
Paul Hewlett - CottonPickinMinds - www.cottonpickinminds.co.za
Tel: +27 21 852 8812 Cel: +27 84 420 9282 Fax: +27 86 672 0563
--
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