experience with max block erase

Herman Oosthuysen Herman at WirelessNetworksInc.com
Fri Jan 18 11:09:48 EST 2002

Well, if you have to write data to flash continuously, then you are using
the wrong media.  Flash is designed for stuff that doesn't have to change

Anyhoo, getting a million or more cycles from flash is not unrealistic, but
then you probably would get some failures in some products and the erase
cycle time would get unacceptably slow eventually.

The important thing to understand is that a flash disk drive isn't one...

BTW, I like your writeups Vipin - it is well presented.
Herman Oosthuysen
Herman at WirelessNetworksInc.com
Suite 300, #3016, 5th Ave NE,
Calgary, Alberta, T2A 6K4, Canada
Phone: (403) 569-5688, Fax: (403) 235-3965
----- Original Message -----
From: Vipin Malik <vipin.malik at daniel.com>
To: Herman Oosthuysen <Herman at WirelessNetworksInc.com>
Cc: dennis noermann <dennis.noermann at noernet.de>;
<linux-mtd at lists.infradead.org>
Sent: Thursday, January 17, 2002 2:41 PM
Subject: Re: experience with max block erase

> Herman Oosthuysen wrote:
> > 100 000 cycles is lot.  You have to erase the chip about ten times per
> > continuously for 100 years to reach that number...
> Let's state 100K cycles another way:
> for a 8mbit chip (1024KB)
> It's only 100K * 1024KB of data life (assuming a circular use- which is
> best case and what you will get with wear leveling).
> If you want your product to last 8 years (pick a number), then the max
> rate that you can send to the flash chip is "only":
> 100000 * 1024/(8*365*24*60*60) = 0.4KB/sec!
> That's not a lot. This does not even take into account the extra data
> due to the overhead of any filesystem one may be using. Tack in another
20% for
> that (not unusual for JFFS2 system- it depends on write sizes- this
assumes a
> small write size/write) then the data rate falls to 0.32KB/sec
> OR let's say that the system is generating data (that needs to be saved to
> flash) at the rate of 10KB/sec (not very high number too), then the life
of the
> system is only 0.32years! (Yikes!)
> Vipin
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