Petter Adsen wrote: > Reading your previous mails make me a little worried, though. It is > only used as a sort of semi-online backup, that I connect when I run > the backup, but my main backups are on bluray-discs. Now I begin to > wonder if I should invest in another drive for backing up stuff, but I > would still want it to be removable.
In the environment you described I would not be worried. I have never
lost any data on my USB mounted disks. You sound like you are
mounting your device for backup, using it, then unmounting it until
needed again. I have never had any problems doing that. I think you
could continue that without any hesitation.
In my case leaving a USB disk *mounted* for a long time and in active
use always resulted in the device eventually (month, two months)
reporting I/O errors which caused the kernel to kick the device out of
the system. I would need to power cycle the enclosure. After a power
cycle and a remove and replace then I could mount it again.
I have never lost any data when the kernel has kicked the USB device
out of my system. It simply caused me to need to manually remove and
insert the USB again. That makes it for a very unreliable system for
me since I value systems not crashing. But I never lost any data.
Previously the oldest USB enclosures would not pass through SMART
commands to the disk. A disk in a USB enclosure would be impossible
to use with SMART. ('smartctl -i /dev/sdg') But newer models now
support passing these commands through. I am just noting it as
another "hacky" thing about the cheap enclosures.
> That means I have to decide between eSATA and IEEE-1394 as interfaces.
> Only this machine has eSATA, I think, while both machines I might want
> to connect it to has Firewire. Which of these would be the best choice
> from a technical standpoint, and do they work well with Linux? I'd
> imagine eSATA would simply be seen as a SATA device?
I like eSATA as it is simply an external SATA. For enclosures that
simply cable the SATA to the drive it is as reliable as an internal
SATA drive.
HOWEVER! It is a big however. I can't find any _new_ eSATA
enclosures that are not also USB enclosures and do not now include
active electronics in the connection between the eSATA and the drive.
That's bad IMNHO. It introduces cheap electronics in the disk path
that is unwanted and unneeded.
I have an older eSATA without any active electronics and it has been
100% good. IF I could find more of those that is what I would buy.
Unfortunately the newer eSATA interfaces I have acquired now have the
cheap electronics in between. I haven't any data showing they cause
problems but I am suspicious. Personally being an EE my plan if I
need one is to cut-n-jumper around it. Simply route the SATA cable
directly to the drive to avoid any problem with the cheap electronics.
I doubt non-EE types would want to go that route however. I can only
submit a general caution.
> Might it also be better to go with a little bit more expensive
> enclosure?
How will you know if money equals value? It is a Market for Lemons.
http://en.wikipedia.org/wiki/The_Market_for_Lemons
I can't recommend spending more money. The odds are good that it
would be a waste of money.
Bob
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