Using a USB thumb drive for backups?
in [Mac Systems]
|
From: isw on 20 Dec 2009 01:38 In article <0001HW.C752F146001B12EDF0182648(a)nntp.charter.net>, Tim Murray <no-spam(a)thankyou.com> wrote: > nospam wrote: > > In article <0001HW.C752A1CD00087270F0488648(a)nntp.charter.net>, Tim > > Murray <no-spam(a)thankyou.com> wrote: > > > >>>> Care to back your opinions up with facts? A Google search supports > >>>> everything Tim and I said. > >>> > >>> cites? > >> > >> Simply search for "flash memory" followed by any word such as lifespan, > >> cycles, destructive, et al. > > > > flash memory having a limited life is not in dispute. > > > >>> memory circuits don't spark and nothing is vaporized. > >> > >> I didn't say memory circuits spark; I said connections spark, and they do, > >> and then I said the flashing circuit in a thumb drive is destructive. > > > > connections do not spark unless they're poor connections. > > I'm using spark in the sense of an electron jumping from one contact to > another as it gets in range. All connections spark but one exception: When > the distance between contacts closes up so quickly that an electron does not > have time to jump. Most of the engineers I've known (in over 40 years of being one or managing them) would only call it a "connection" if the pieces of metal were in actual, physical contact, with nothing separating them. Isaac
From: Tim Murray on 20 Dec 2009 01:43 isw wrote: > Tim Murray <no-spam(a)thankyou.com> wrote: >> >> I'm using spark in the sense of an electron jumping from one contact to >> another as it gets in range. All connections spark but one exception: When >> the distance between contacts closes up so quickly that an electron does >> not have time to jump. > > Most of the engineers I've known (in over 40 years of being one or > managing them) would only call it a "connection" if the pieces of metal > were in actual, physical contact, with nothing separating them. > I agree. I was referring to the time just before the actual connection is made or just after it breaks. I kinda thought the "gets in range" should have made that clear.
From: Andrew Brydon on 20 Dec 2009 05:52 Once upon a time, Tom Harrington <tph(a)pcisys.no.spam.dammit.net> 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? > >Others have discussed the potential cons. I'll just suggest that most >of these can be avoided by using multiple drives for redundant backups. >It's unlikely they'd all fail at once, so even if one was to wear out or >get zapped or go through the laundry or something you'd still have >others to fall back on. Get 2 or 3 (they're cheap these days) and >rotate them. > I do this. As a "normal" domestic user I have a weekly backup to extenral USB, a subset burned tp CD and taken off-site (okay, so maybe that's not normal) but on a daily basis the likeliest to change sub-subset is flashed to a 8Gb USB pen. Rotated if necessary. [iCal triggers an Applescript copy command at 4am each morning, since you weren't asking.] -- Andrew Brydon Life is just the beta-version of death
From: Jolly Roger on 20 Dec 2009 11:21 In article <isw-307662.10204119122009@[216.168.3.50]>, isw <isw(a)witzend.com> wrote: > In article <tph-7E4F37.23571618122009(a)localhost>, > Tom Harrington <tph(a)pcisys.no.spam.dammit.net> wrote: > > > In article <isw-C0CD34.21281918122009@[216.168.3.50]>, > > isw <isw(a)witzend.com> wrote: > > > > > It's on the Mac of a barely-capable user who works with critical > > > (financial) data (she understands the finances; just not the computer), > > > and so absolutely cannot be trusted to do any backing up in a reliable > > > fashion. The backup app launches at login, and runs continuously, waking > > > up once a week to copy the folders I told it to copy. > > > > Sounds like a candidate for Dropbox, <http://www.dropbox.com/>. > > > > Have her put the files in the Dropbox folder, and the software will > > silently mirror it to a Dropbox account (and optionally to other > > computers) whenever it changes. She doesn't need to "do" backups, > > they'll just happen, and if/when disaster strikes the files are easily > > recoverable. > > backuplist+ works without intervention (once I set it up); I'm just > looking for the best option for external storage. I'm leaning heavily > towards a 2 or 4 Gig USB Thumbdrive at this time. > > Isaac If it were me, for sensitive backup data, I'd probably go with a thumb drive that can self-destruct the data if it gets into the wrong hands: <https://www.ironkey.com/> -- Send responses to the relevant news group rather than email to me. E-mail sent to this address may be devoured by my very hungry SPAM filter. Due to Google's refusal to prevent spammers from posting messages through their servers, I often ignore posts from Google Groups. Use a real news client if you want me to see your posts. JR
From: Jolly Roger on 20 Dec 2009 11:32
In article <191220091144356673%nospam(a)nospam.invalid>, nospam <nospam(a)nospam.invalid> wrote: > In article <jollyroger-657BA0.09542819122009(a)news.individual.net>, > Jolly Roger <jollyroger(a)pobox.com> wrote: > > > USB bus-powered enclosures have a design flaw: the power supplied by the > > USB bus is barely enough for todays faster, more power-hungry drives. That would be your opinion. My opinion is there are still drive being sold today that require more power. The fact that such drives come with dual Y-split USB cables lends credence to my opinion. They require more power than one USB port can supply. Unfortunately, I suspect some laptops may not have dual USB buses with separate power supplies, which could result in occasional low power situations for such drives. > actually, recent drives use less power than older drives. usb is > sufficient for normal operation, but not enough to spin it up. > > > To make matters worse, at certain times, the power delivered by USB ports > > can fluctuate. > > only if the host is defective. I disagree. Power can fluctuate if devices are aded to or removed from the same bus. And it is my belief that power can fluctuate at other times on a laptop where battery drain comes into play. > > When a hard drive does not receive enough power during a > > write, unpredictable things may occur, including data corruption on the > > drive. Laptops are especially prone to USB bus power fluctuations. > > no, they're prone to not being overspeced. desktop computers have a > much higher power budget and can easily overspec the usb ports. Regardless, my opinion is the power delivered USB ports on laptops are more prone to fluctuation. > all usb hosts are required to supply 500ma, and most drives need about > 1a to spin up the drive, but can run fine once spinning on 500ma. since > usb hard drives are common, some computers provide more than required > 500ma. Unfortunately neither of us has physically monitored the power output of each USB port on all of Apple's currently-shipping MacBook line through all of the different phases of startup and under different usage scenarios. So neither of us can categorically state that 500ma is consistently delivered to all USB ports on these machines at all times. I suspect such is not the case. I suspect this is what caused corruption of my then-USB-connected drive multiple times in a couple months. The same hard drive, placed into a Firewire enclosure hasn't had a single instance of corruption since then - for the past 8 months or so. > > I have experienced data corruption several times with a USB bus-powered > > enclosure connected to my MacBook Pro used for Time Machine backups. I > > can tell you from experience that finding out your Time Machine backup > > is corrupt when you most need it is not a pleasant experience. I refuse > > to use a USB bus-powered enclosure anymore. For me it's Firewire-only, > > and no USB unless absolutely necessary - and then only with an external > > power source for backups. > > that could be due to any number of things. i had a time machine archive > with a desktop drive get corrupted. time machine is not all that > reliable. Too coincidental for my tastes - see above. -- Send responses to the relevant news group rather than email to me. E-mail sent to this address may be devoured by my very hungry SPAM filter. Due to Google's refusal to prevent spammers from posting messages through their servers, I often ignore posts from Google Groups. Use a real news client if you want me to see your posts. JR |