Backup and recovery

David Both david at both.org
Sat Dec 19 13:50:53 EST 2015



On 12/19/2015 01:25 PM, AC wrote:
> On 2015-12-19 05:59, Jean-David Beyer wrote:
>> On 12/19/2015 08:37 AM, Mike or Penny Novack wrote:
>>> On 12/18/2015 9:16 PM, Jean-David Beyer wrote:
>>>> I do a full backup of almost my entire system every night to an external
>>>> USB-3 hard drive. I do a full backup of almost my entire system every
>>>> week onto magnetic tape that I keep in another room from where my
>>>> computer is. I do a full backup of almost my entire system every week
>>>> onto magnetic tape that I keep in my safe deposit box at my bank.
>>> THIS is an example of doing backup (although using obsolescent
>>> technology, since a modern external hard drive the size of one computer
>>> tape cartridge holds FAR more data and could rotate one to the other
>>> room, bank vault, etc. ---- I keep a second copy in a fire box inside a
>>> dead fridge in an outbuilding.).
>> You are right that magnetic tape technology is obsolete, although the
>> tapes I use are VXA tapes originally produced by Ecrix. They are
>> extremely reliable, and I can fit many months of these tapes in my safe
>> deposit box, whereas I can put only a very few WD-Passport drives in
>> there. I like to keep a year's worth there (12 cassettes take up much
>> less space than 12 Passports). OTOH, when these tape drives quit, that
>> is over as no one makes tape drives like these anymore. That is why I am
>> using the Passports for the shorter term (daily) backups.
>>> You have LOTS of user data on your computer system besides gnucash data.
>>> Rather silly to have each application responsible for backing up the
>>> data with which it is associated.
>> Absolutely! By Murphy's law, each application would use a different
>> backup strategy, different storage formula, etc., so that restoring
>> would be completely unmanageable.
>>
>>> You wouldn't expect your word
>>> processor to be doing the backups for the documents it created, would you?
>>>
>>> The backups made by gnucash are really intended for use with problems a
>>> short time back (since the last full data backup). If you are not doing
>>> regular backups then sooner or later you will lose your data. It's not
>>> if computers fail but when. If you do not have a "tech support" to do
>>> your data backups and restores then you have to learn how to do it
>>> yourself. Part of successfully using a computer.
>
> Tape is not obsolete.  LTO (Linear Tape Open) is the current standard.
> A single LTO-6 tape which is nominally the size of a USB external hard
> drive case that fits a standard 3.5-inch hard drive (not a laptop sized
> 2.5-inch drive) can hold 2.5 TB uncompressed.  LTO-7 due out in late
> 2016 is the same size tape with a 6.0 TB uncompressed capacity.  Nominal
> compression is 2.5:1 so the LTO-6 2.5 TB becomes 6.25 TB and the
> upcoming LTO-7 will be about 15 TB.
>
> The advantage of tape is that more media can be physically added to a
> tape design (possibly making the cartridge slightly larger) without
> changing the underlying technology.  Hard drive read/write head
> technology coupled with the magnetic coating technology requires
> significant leaps to achieve higher write densities in what is a very
> restricted form factor (the drive can't change shape or it won't fit
> into the machines).  The tape technology can be updated as well (better
> materials, better hardware) to increase data density but storage size
> doesn't stay coupled to technology advancement.
>
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I have used many tape formats over the years. They all work well for a 
while and then start failing - and they all do. When they do, regardless 
of the form factor or tape format, it is usually not possible to locate 
a new device of the correct type. At least not for a reasonable sum.

I have also tried various types of Iomega type devices such as Jazz and 
REV drives. All eventually fail. With these devices, if one disk fails, 
it damages the heads of the drive so you need to replace both the drive 
and the disks even if the same device type is available. Also very 
expensive.

I have found that the most reliable devices in the first place, and the 
easiest to obtain more of are simple external USB hard drives. I have 
been using them now for several years and have yet to have one fail for 
any reason. I bought five on sale at Costco and rotate them on a regular 
basis, always putting the latest in the safe deposit box. These drives 
also have a far larger capacity than any tape on the market. And if one 
ever does fail, there is no problem with the others and I can simply 
replace the failing drive with another of any type at all with no 
worries about physical compatibility between a drive and tape/disk.

Just my personal experiences.

Thanks!

> --
>
>
> *********************************************************
> David P. Both, RHCE
> Millennium Technology Consulting LLC
> Raleigh, NC, USA
> 919-389-8678
>
> dboth at millennium-technology.com
>
> www.millennium-technology.com
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*********************************************************
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1931
*********************************************************
David P. Both
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