[ltp] ThinkPad 600 Second Hard Drive option

[unlisted]

On Sat, 2002-07-06 at 17:45, peter nol wrote:
> I want to stripe- store my information on 2 drives- that's twice as
> secure. Just so that if one drive dies, the other saves my info. Unless
> the power blows out, then both drives will probably be dead :)
> So that means i get the CD out and get an adapter for a HD and use that?

On Saturday 06 July 2002 09:37 pm, Robert A Munro wrote:
> If you want to duplicate your data on two drives, that's called...
> mirroring, not striping.  Striping is for performance, not security.
>
> But I'm not certain that _any_ notebook IDE controller does mirrors.

On Sun, 2002-07-07 at 07:59, peter nol wrote:
> Thanks. Yeah, i'll do both. That's what i meant.

okay, this is getting silly/ridiculous.  so you are saying that you want
both stripping AND mirroring?

stripping + mirroring = raid 0 + raid 1 = raid 0+1

for more info, look here: <http://www.acnc.com/04_01_0p1.html>

found that site a long time ago through webopedia
<http://webopedia.com/TERM/R/RAID.html>.  a good resource for general
internet/computer info.

back to raid 0+1: that requires a minimum of four drives.  on a laptop? 
possible.  likely?  doubtful.  practical?  no.

if four harddrives on a laptop is even possible (without resorting to
pcmcia drives dangling everywhere on your desktop), you could use
software raid.  an ide controller doesn't necessarily have to support
raid.  (most cheap/inexpensive desktop ide "raid" controllers are just
software-raid implementations anyways. 
<http://www.anandtech.com/storage/showdoc.html?i=1491>)

the software-raid howto does make mention of raid 0+1 (incorrectly
called "raid 10"
<http://www.tldp.org/HOWTO/Software-RAID-HOWTO-7.html#ss7.4>, so i
assume it is possible.  i don't have any real experience with linux
software-raid, just what i've briefly read out of my own curiosity, so i
don't know if you can layer raid levels (raid 0 + raid 1) or if in the
howto raid 0 was hardware-based and raid 1 was software-based.  probably
a thorough reading of the howto would answer that question.

so, in conclusion: you probably just want/need fault tolerance, so
mirroring (raid 1) should be enough.  actually, performing
regular/scheduled nightly backups (to a 2nd drive or server) could be
enough, depending on how often your data undergoes massive changes
during the work day, and if you have high-speed connections (2nd drive,
lan, broadband) at night.

(heck, create a low priority, +19, root cron job that copies all your
data from one drive to another drive two, maybe three, times a day. 
possibly create a tarball to conserve space or use "find -cmin" to find
only the files that have changed since the last backup.  maybe rotate
between several directories so that you can keep multiple backups, but
don't have too many, like what logrotate does.  anyways...)


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