Using a USB thumb drive for backups?
in [Mac Systems]
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From: isw on 18 Dec 2009 17:07 In article <jollyroger-98460E.12480418122009(a)news.individual.net>, Jolly Roger <jollyroger(a)pobox.com> wrote: > In article <isw-AC315E.10332418122009@[216.168.3.50]>, > isw <isw(a)witzend.com> wrote: > > > Not with Time Machine, but with "backuplist+", which does them once a > > week. > > > > Pros/cons? > > What if you lose it? Perhaps <https://www.ironkey.com> is the answer. Same as if I lose the hard drive I'd be replacing it with... Isaac
From: isw on 18 Dec 2009 17:10 In article <fmoore-9670B1.16410918122009(a)feeder.eternal-september.org>, Fred Moore <fmoore(a)gcfn.org> wrote: > In article <isw-AC315E.10332418122009@[216.168.3.50]>, > isw <isw(a)witzend.com> wrote: > > > Not with Time Machine, but with "backuplist+", which does them once a > > week. > > > > Pros/cons? > > NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO! NO!... > > ...if by 'backup' you mean a REAL backup in the sense that we usually > use it here (secure copy of data from which the data can be recovered > _uncorrupted_ at some time months or even years in the future), and not > just an extra convenience copy or a copy to sneakernet to another > machine. > > RAM chips are FRAGILE! Static electricity either by a single jolt or > through accumulated smaller zaps will KILL integrated circuits. The > microscopic connections on integrated circuits are TINY (think > nanometers). Every exposure to high voltage (and the voltage doesn't > have to be that high) vaporizes a small amount of the metal in one or > more of the connections. Sooner or later the last molecule of gold or > copper escapes into the cosmos from which it came, and the RAM chip is > hosed. Some of the better constructed thumb drives claim to have > electrical circuit buffering to extend their lives, but they are still > vulnerable. > > Strong magnetic fields and x-rays can also corrupt/destroy integrated > circuits. > > Why aren't the RAM chips inside your computer just as fragile? THEY ARE! > except that the computer manufacturers take a number of steps to protect > all of the semiconductors inside the machine. > > And none of the above addresses losing a thumb drive because it falls > out of your pocket when you go for your car keys, or other numerous and > mundane accidents. > > For more info on semiconductors and static electricity, Google can be > your guide. Probably a good place to visit for accurate information on thumb drives, too... Isaac
From: Tim Murray on 18 Dec 2009 18:02 isw wrote: > Not with Time Machine, but with "backuplist+", which does them once a > week. > > Pros/cons? > Flash memory, the kind used on thumb drives, is not the same as the chips used inside the computer. Flash memory wears out: It is the "flash" -- the signal that causes the bit to be locked in -- that eventually wears out the chip. Some thumb drives can detect a bad bit and compensate, but this only postpones the inevitable (see http://en.wikipedia.org/wiki/Wear_levelling). Many more expensive SLC-type thumb drives are rated for 300,000 cycles, but cheaper MLCs are only around 10,000. Flash has a problem disks don't, in that flash drives move your data around with every update. Every time a flash drive writes a page, it has to erase the entire block that page is in. What happens to the data in the block? It gets read and rewritten along with the new page to a new location. The map that keeps track of where your data is rapidly gets very complex and itself is regularly read and rewritten. If the drive's physical to virtual block map gets corrupted there is no way to recover data. And that critical map is getting read, updated and rewritten with every file update. While I would recommend an external disk for a backup, statistically you're probably okay with a USB as a backup, but not as a "working" drive. The reason is that if your computer goes south the chance that your thumb drive is also bad is small, unless what killed your computer was, say, a lightening strike that happened while your thumb drive was installed.
From: Tim Murray on 18 Dec 2009 18:07 nospam wrote: >> The microscopic connections on integrated circuits are TINY (think >> nanometers). Every exposure to high voltage (and the voltage doesn't have >> to be that high) vaporizes a small amount of the metal in one or more of >> the connections. Sooner or later the last molecule of gold or copper >> escapes into the cosmos from which it came, and the RAM chip is hosed. >> Some of the better constructed thumb drives claim to have electrical >> circuit buffering to extend their lives, but they are still vulnerable. > > no Every connection causes a spark. Some metal is lost in vaporization (the metal sputters and is carried away in an aerosol) and some to excitation. The melting point of the metal is a major factor. Gold has great conductive properties but a low melting point and a low life-span. The flashing circuit in a thumb drive is destructive, only for a different reason.
From: nospam on 18 Dec 2009 18:39
In article <0001HW.C751755400171A5BF0182648(a)nntp.charter.net>, Tim Murray <no-spam(a)thankyou.com> wrote: > >> The microscopic connections on integrated circuits are TINY (think > >> nanometers). Every exposure to high voltage (and the voltage doesn't have > >> to be that high) vaporizes a small amount of the metal in one or more of > >> the connections. Sooner or later the last molecule of gold or copper > >> escapes into the cosmos from which it came, and the RAM chip is hosed. > >> Some of the better constructed thumb drives claim to have electrical > >> circuit buffering to extend their lives, but they are still vulnerable. > > > > no > > Every connection causes a spark. Some metal is lost in vaporization (the > metal sputters and is carried away in an aerosol) and some to excitation. The > melting point of the metal is a major factor. Gold has great conductive > properties but a low melting point and a low life-span. um, no. > The flashing circuit in a thumb drive is destructive, only for a different > reason. flash memory does have a limited life but it's far higher than what someone is realistically going to reach. they'll probably want a larger capacity device before it fails (or lose it). |