Gentoo Archives: gentoo-user

From: David Relson <relson@×××××××××××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Re: rsync to a USB stick
Date: Mon, 31 May 2010 02:27:38
Message-Id: 20100530222619.340ccce1@osage.osagesoftware.com
In Reply to: [gentoo-user] Re: rsync to a USB stick by Grant Edwards
1 On Sun, 30 May 2010 14:20:36 +0000 (UTC)
2 Grant Edwards wrote:
3
4 > On 2010-05-30, Neil Bothwick <neil@××××××××××.uk> wrote:
5 > > On Sat, 29 May 2010 07:59:31 -0400, David Relson wrote:
6 > >
7 > >> Indeed flash drives _do_ have a lifetime. My recollection is that
8 > >> it's in the thousands of writes if not the hundreds of thousands
9 > >> of writes. Assuming a life of 1,000 writes and you backup once
10 > >> daily, that's 3 years of backups. 10,000 writes would be 30
11 > >> years. Of course if you backup every hour, 10,000 writes is a
12 > >> year (or so).
13 > >
14 > > You're assuming that each backup only writes once, which is far from
15 > > true. If you mount a drive with the sync option, the FAT is updated
16 > > for every block you write, so even a single file can cause
17 > > thousands of writes to the same location.
18 >
19 > And you're assuming that the flash controller chip in the USB drive
20 > doesn't do wear-leavelling.
21
22 FWIW, I have enabled synchronous writes for a Disk-On-Module (SSD)
23 formatted ext2. It makes writing take significantly longer and I have
24 had a DOM go bad (become unusable). Admittedly, I don't know whether
25 the DOM does wear-levelling and I don't know the underlying cause of
26 the failure. In any case it was "Not Good (tm)" ...