Re: HD Backup

["Robert G. (Doc) Savage" <dsavage@peaknet.net>]

On Sun, 2006-01-01 at 10:49 -0500, Bryan J. Smith wrote:
> On Sat, 2005-12-31 at 19:27 -0600, Robert G. (Doc) Savage wrote:
> > If raw capacity in a small package interests you, then consider a 500GB
> > EIDE drive
> 
> <anal note/not a big deal/just FYI>
> EIDE is a Western Digital trademark, and really a legacy one -- pre-
> UltraDMA modes.  The modern term is ATA drive.
> </anal node>

Oh, puhleeeeze Bryan. An unprotected, unenforced, and widely used
"trademark" is just a word. You completely missed my point, which was to
distinguish EIDE drives from their SATA brethren, for which external
enclosures are still rather uncommon.

> > in an external USB2 enclosure. I recently picked up a Hitachi
> > 7K500 drive
> 
> Just know that the Hitachi 500GB is a 5-platter drive.  The last 1" ATA
> hard drive to sport 5-platters was the IBM Deskstar 75GXP.  ;->
> 
> The Seagate 7200.9 500GB uses 4-platters.

Upon further checking, you are correct. Note that Seagate's new vertical
recording media (remember 2.88MB floppies with barium ferrite media?) --
the kind used in my new Momentus 120GB 2.5" notebook drive -- if applied
to 3.5" form factors could reduce the platter count for 500GB drives to
just 1. (Incidentally, I just measured the surface temperature of the
metal enclosure containing my Hitachi drive: 102 degrees in a 69 degree
room. Warm to the touch, but good for an enclosure with no fan.)

> > Regarding FAT32, my 500G drive is formatted with NTFS so I can move
> > stuff to/from Windows systems and requires Paragon's NTFS for Linux
> > read/write driver (http://www.ntfs-linux.com/). After overcoming an
> > early problem which Paragon fixed straight away, it now works perfectly.
> > I do have to recompile every time I upgrade the kernel (just like
> > VMware), but a script makes that almost trivial.
> 
> NTFS was _never_ designed for removable media.

Ahem... What filesystem was?

> There are Security ID (SID) and other ties to the Registry or Domain
> Security Accounts Manager (SAM) of each NT system.  You could eventually
> get a corrupted filesystem as a result of modification by files from one
> system by another -- when they are non-domain workstations, or the files
> are either owned by accounts not in the domain, or two different domains
> (without a trust).

Forgive me for being blunt, Bryan, but this is pure FUD. NTFS filesystem
corruption, while guaranteed when using the NTFS driver that comes with
Linux in read/write mode, is nonexistant with the commercial Paragon
driver. Its use is transparent except (as you've noted) for permissions
and ownership on individual files, a characteristic shared to one degree
or another whenever files are copied from one type of filesystem to
another. Of course, the solution to the permissions/ownership
preservation problem was solved years ago with tar.

Not to belabor the point, but we live in the most litigious nation in
the world. Paragon would not dare market their NTFS for Linux in America
if there were any possibility of being sued for damages over data
corruption resulting from its use.

In the real world of daily experience I can point to many dozens of
NTFS-formatted LaCie external drives in service in USTRANSCOM at Scott
AFB. Quite a few are used as software distribution sources and backups
for large numbers of PCs and servers, both non-domain and members of
multiple domains. The SID & SAM problems you refer to simply haven't
been seen here.

The only problem I've ever seen with any of those LaCie devices was a
string of bad sectors that developed up near the start of the one active
partition on the 120GB drive in my unit. This was a purely hardware
fault which I fixed with a low-level format followed by a certification
pass to map out bad sectors. I used ddrescue and dd to strip and restore
the partitions; chkdsk at initial mount took care of the gaps where the
bad sectors had been.

> The workaround for this is to use Dynamic Discs (Logical Disk Manager,
> LDM, Disk Label -- which appears as a slice/partition in a Basic Disc,
> legacy DOS/BIOS partition table, of type 42h), which stores some basic
> SID info outside the filesystem.  Of course, you can still get
> permission loss as a result, but it will prevent you from getting a
> corrupted filesystem.  Of course LDM disk labels can act weird when
> moved across systems, because Microsoft never supported them for
> removable media (let alone not portable systems like notebooks either).
> 
> I typically recommend formatting an external disk with Universal Device
> Format (UDF) which is supported by just about every modern platform (I'd
> format it UDF under Linux).  Although I've never tried it on a 500GB
> volume, typically just sub-100GB ones.

Unless I'm terribly mistaken, UDF is a read-only filesystem designed for
DVDs, CD-Rs, and WORM drives and would not be suitable on an external
hard drive in Ray's situation.

Lacking an ext3 driver for Windows, NTFS is today the most capable
journaling filesystem for removable media larger than thumb drives. If
you want to freely exchange files between Windows and any other system,
you MUST use a Windows-supported filesystem simply because Microsoft
refuses to support non-Windows systems. (And please don't quibble with
me about FAT12/16/32 not being Windows filesystems because Microsoft can
no longer legally restrict their use by non-Windows systems.)

I stand by my suggestions to Ray. They're based on real world experience
I know to be true. Ray is free to accept or reject them without hurting
my feelings in the slightest.

-- Doc
Robert G. (Doc) Savage, BSE(EE), CISSP, RHCE | Fairview Heights, IL
Fedora Core 4 kernel 2.6.14-1.1653_FC4 on a P-III/M IBM Thinkpad A22p
            ** Bob Costas for Baseball Commissioner **


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