[Elecraft] "Bit image backup": "Safe sectors"

Tue May 22 18:52:16 EDT 2012

dd or dd_rescue copies of SSD's are fine and no problem. 
The controllers hide all the fancy wear levelling stuff from the
computer and present a disk that to the OS looks just line any other
sata hard disk. 

dd_rescue is a variant of the linux dd utility which can deal with disks
that ate not 100% healthy 
see 
http://www.garloff.de/kurt/linux/ddrescue/

you will find dd and dd_rescue along with a bunch of other useful tools
for copying partitions/disks on the knoppix distribution which is a
bootable 'live cd' or can be used from a USB stick 

http://knoppix.net/

Trinity rescue kit is supposed to be very good too 

http://trinityhome.org/Home/index.php?wpid=1&front_id=12

On Tue, 2012-05-22 at 15:03 -0700, Jack Brindle wrote:
> John;
> 
> Be very careful with a sector-by-sector backup utility if you decide  
> to use an SSD. Solid State Drives constantly are moving sector  
> locations around in order to avoid writing to the same flash location  
> too many times. This occurs whenever a file needs to be updated or  
> rewritten, and is especially true of the directory sectors. Because of  
> this a backup may catch a file relocation in mid move, or more often  
> catch a directory update while it is being moved, The result will be a  
> completely useless backup. We discovered this recently when a friend  
> needed to restore his system from a backup.
> 
> The answer is to use a normal file-oriented backup instead of a sector- 
> by-sector backup. Those backups are very much useful when needed. With  
> the trend to replace disks with SSDs, especially in laptops, this will  
> become very important.
> 
> For those wondering, TIme Machine is indeed a file backup and not  
> sector-by-sector. I recommend it whole heartedly!
> 
> Jack Brindle, W6FB
> 
> 
> On May 22, 2012, at 11:22 AM, John Ragle wrote:
> 
> > Hi, Jim...
> >
> >     There are several programs that make literal copies (mirror  
> > copies)
> > of disk contents. This includes the OS and all program files as well  
> > as
> > data...
> >
> >     I happen to have been using one called "Macrium Reflect
> > Professional" for the last few years. It produces a bit-for-bit  
> > literal
> > image (a mirror copy) of the TOTAL contents of one or more hard  
> > drives,
> > and can re-load such images. It does much more than copy data files.  
> > At
> > present, I am using a PC with 2 inboard hard drives, each of 250 GB
> > capacity. One of these is my WIN7 Ultimate OS and associated files
> > (including programs, etc), and is about 80 GB in total content. The
> > second is my Ubuntu 11.10 OS and a somewhat smaller collection of  
> > files
> > (including programs, etc.) I back up the former almost daily onto a  
> > 1 TB
> > external USB hard drive, and somewhat less frequently onto a Sandisk  
> > 64
> > GB stick...the 80 GB on the C:\ drive fit nicely onto the 64 GB stick
> > with the compression used by Macrium. The rate-determining step in  
> > these
> > USB-based devices is the USB transfer rate itself; 80 GB takes about  
> > 25
> > minutes to back or restore, and I do it last thing at night, letting
> > Macrium close down the PC when finished.
> >
> >     If I had a third drive bay, I would probably choose to back up  
> > onto
> > a third drive...hard drives have become so inexpensive that you can
> > practically use them like floppy drives. This would be significantly
> > faster, about 10-12 minutes for the 80 GB contents of C:\
> >
> >     A while ago, I used a Sparc 20 with a shoebox tape drive and "DAT
> > Tapes," but that had little to do with my ham radio operation. These
> > were unsatisfactory because the error rate was significant. I also  
> > tried
> > using an elderly PC as a network server at home on our LAN. That too  
> > was
> > somewhat cumbersome. My wife is an active software developer (vide the
> > "OWL" system from Cengage), and separately uses a version of Macrium
> > onto a 1 TB external drive, but much of her work is stored on a
> > corporate "cloud," and hopefully backed up there as well.
> >
> >     I do not have a high opinion of "Windows Restore" -- it is
> > significantly more involved to use than is Macrium Reflect.
> >
> >     An advantage (to me the most significant one) of doing a bit-image
> > backup is that when it comes time to restore program files (i.e. .exe
> > files, etc), one does not have to search out the distribution media  
> > and
> > play "baking cookies" with those media for hours to rebuild the  
> > system.
> >
> >     A disadvantage of doing a bit-image backup is that in the absence
> > of good "garbage collection" one keeps using the same general  
> > structure
> > over and over again...a case can be made for rebuilding from scratch
> > (not from the bit image) on a regular basis...some have suggested  
> > once a
> > year, at least.
> >
> >     The Linux crowd can tell you of several useful Linux based
> > utilities for total backup, restore, partitioning, etc...I won't
> > enumerate them here, though many of them are very useful.
> >
> >     In general, I don't favor running anything off the "cloud." My ISP
> > is sometimes down for 1 or more hours, and that mode of dis-operation
> > would leave me in the cold. Moreover, in view of the spate of  
> > successful
> > hacking attacks, I don't trust cloud security. If I disconnect from  
> > the
> > internet, the only ways someone can hack me are via my WiFi or to
> > physically break into my home. I have taken pains to barricade the
> > former. The latter takes care of itself in the usual way.
> >
> >     Hope this answers your questions....
> >
> > John Ragle -- W1ZI
> >
> > =====
> >
> > On 5/22/2012 12:59 PM, James Robbins wrote:
> >> John,
> >>
> >>
> >>
> >> Could you be more specific about your process for "bit image  
> >> backup" and
> >> "safe sectors"?  Program you use?  What files you choose to  
> >> backup?  Whether
> >> Windows Restore program is or is not a suitable substitute?  Thanks.
> >>
> >>
> >>
> >> 73,
> >>
> >> Jim Robbins
> >>
> >> N1JR
> >>
> >>
> >>
> >> "It is vitally important to practice "safe sectors." A bit image  
> >> backup
> >> takes only a few minutes, and can be made on an auxiliary hard  
> >> drive or a
> >> jump drive."
> >>
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> >>
> >>
> >
> > -- 
> > Sent from my lovely old Dell XPS 420
> >
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-- 
73
Brendan EI6IZ 