[GTALUG] Portable Backup Drive Compatible with Linux (and Recommended Backup Software)

Lennart Sorensen lsorense at csclub.uwaterloo.ca
Fri Feb 3 12:56:27 EST 2017


On Fri, Feb 03, 2017 at 12:42:47PM -0500, D. Hugh Redelmeier via talk wrote:
> 
> | From: Jason Shaw via talk <talk at gtalug.org>
> 
> | I personally like the form factor of Western Digital Passport drives as
> | they are USB powered,  USB 3, and small form factor.  I get decent
> | performance out of it, and so long as your backups are incremental, after
> | the initial sync, the future changesets should be fairly small.
> 
> Thoughts about external drives:
> 
> - FireWire is gone.  Let that be a lesson.
> 
> - eSATA is probably going to disappear.  It isn't common.  For
>   longevity, pick USB 3.

I find it is in lots of places.  I do have external backups drives with
both USB3 and eSata which I find convinient.  That is on a larger one with
an external power supply though.  I haven't seen too many eSATAp drives.

> - eSATA has a couple of advantages and disadvantages
>   + faster than USB2 (important for older computers)
>   + makes S.M.A.R.T. features of the drive available to the computer.
>   - hot-plug is very system-dependant and not well documented.
> 
> - 2.5" is so much more convenient than 3.5
>   + one cable vs separate data and power cable

At least with USB3.  With USB2 in the past that wasn't always true.

>   + no power supply brick
>   + physically smaller
>   + bare drives are meant to survive physical shock better
>     (laptops need more robust drives than desktops)
> 
> - the price difference between 2.5" and 3.5" isn't bad

Can't get quite as large drives in 2.5" but that might not be a problem.

> - external drives are usually cheaper than bare drives!  Very odd.

Not what I have seen, although if they are, you might not be comparing
against the right bare drive.  Some external enclosures use lower
spec drives (less cache, lower RPM, etc) since they figure they don't
actually need the performance if connected by USB.  They are not the
primary drive for the system after all.

> - you should size your drives appropriately for your workflow
>   Seagate 4T 2.5" drives are amazingly inexpensive once in a while
>   (I've collected a few at ~$125 + tax).  But a lot of eggs fit in
>   that basket.
> 
> - WD external drives are encrypted.  You cannot take the drive out of a 
>   busted enclosure to recover the data.  Seagate drives are can be taken 
>   out of the enclosure and read (at least until recently; any changes are 
>   unlikely to be announced).  The reason WD does this is probably to 
>   maintain the price premium for bare drives.  It makes a small number of 
>   failure modes worse for WD drives than Seagate drives.

Only some WD drives are encrypted.  Some use a custom connector though
which would be quite a pain.

Apparently some of them they put the USB interface right on the drive
controller board, so it doesn't even have a SATA connector.  This seems
to be the case of the WD element for example.

> - I've bought a few inexpensive NAS boxes.  Very convenient but the
>   firmware gets obsolete and security might be a problem.  They seem
>   fairly slow.
> 
> - USB flash memory sticks are very convenient but their reliability
>   seems unpredictable and bad.
> 
> - assume that all drives fail.  If all your drives are of one model,
>   they may all fail the same way at roughly the same time.  But most
>   backup plans assume that each failure is independent.  OOPS.

Yes backups should be a set of disks in rotation.  You don't want to be
overwriting your only backup while doing a new backup since that means
you have no backup for a while and that could be the moment your main
disk decides to fail.

> - consider using archival CDs or DVDs as a supplement to hard drives.
>   Mag Tape seems to be a gonner.
> 
> - low-acid paper is pretty useful but only for low-volume archiving.
>   Even more so for clay tablets.
> 
> - the only safe archival plan involves regular copying of the data.
>   Copying must include verifying.  "Regular" means at a frequency
>   significantly higher than the expected failure rate of the medium
>   (obsolescence is a kind of failure).  This copying should be
>   scheduled when the previous copy is made to increase the chances
>   that it will actually happen.  Discipline!  This is something I have
>   failed at too often in my half century of playing with computers.
> 
> - pick you filesystem carefully
>   - some may become obsolete
>   - some try to survive limited medium errors
> 
> - archived data needs to be indexed in some way that it can be found.
>   It must be in a format that will be accessible when it is needed.
>   This is a big topic.

All good advice.

Not sure I want to use clay tablets.

-- 
Len Sorensen


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