flash RW limit and M$ re hdd design

  • Thread starter Thread starter someone
  • Start date Start date
Previously someone said:
Interesting reading for the hdd professionals in this group.

"Flash memory has a limited lifespan of around 100,000 read/write cycles.
Heavy users would exhaust that in a couple of years but light users'
notebooks would have up to 40 years before the flash memory wore out, we are
told. "
Click to expand...

These estimations seem wide off the mark. Depends on the filesystem
used and on what you put in there.

If your swap/pagefile resides on flash, it can be gone in a
matter of days. (I know that is tupid, but users will
do it if there are no safeguards against this usage.)

If files keep a "last accessed" timestamp (like practically all
UNIX filesystems, not sure about NTFS), you might loose the flash
in some weeks.

If you use the strategy common for Linux on flash (all in RAM,
write-back every few hours and on shut-down), you will get
in the range of decades.

It is also noteworthy that some flash chips have only 10.000
overwrites, while others have more.

Arno
 
This is all speculation, right Arnie? Who would page to flash? More RAM is
cheaper.

There are flash IDE drives with ECC and bad sector reassigning, used in many
rugged applications. They last years.
 
In Windows, USB flash disks are considered removable media.
You cannot have a swap file on removable media and on a removable device.

"Last accessed" time is also not recorded on them.

On regular disks, with FAT(32) last access time has resolution of 1 day, and
with NTFS 1 hour. This means it won't be updated more often.

In Windows, removable media and removable storage devices have "paranoid"
write-back policy. The data won't be held in write-back cache for long. Not
sure why Linux would behave otherwise.
 
Previously Alexander Grigoriev said:
In Windows, USB flash disks are considered removable media.
You cannot have a swap file on removable media and on a removable device.
Click to expand...
"Last accessed" time is also not recorded on them.
Click to expand...
On regular disks, with FAT(32) last access time has resolution of 1 day, and
with NTFS 1 hour. This means it won't be updated more often.
Click to expand...
In Windows, removable media and removable storage devices have "paranoid"
write-back policy. The data won't be held in write-back cache for long. Not
sure why Linux would behave otherwise.
Click to expand...

I didn't think this was removable flash we are talking about here,
but rather IDE-flash.

Still, it seems this is less of a problem with Windows. Doing
this with any UNIX-like OS will kill the flash pretty fast, since
last-accessed has second reaolution in most UNIX filesystems.

On the other hand, FAT32 has the FAT, where a lot of updates go.
Might still not live very long if used "normally" (whatever that
is...)

Arno
 
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