[seul-edu] Re: Best wm for tiny slow computers?

[Michael Shigorin <mike@lic145.kiev.ua>]

On Wed, Feb 20, 2002 at 07:23:18AM -0500, Ralph M. Deal wrote:
> I've been using dd ON the original/boot to copy the orginal and it
> works!
Sure.  But you get "mounted state" copy, so do "umount -a" before
;-)

> That of course could be the problem;  if dd has to be cached on the hard
> drive due to a small RAM, then the heads reading the original would have 
> to constantly going back and forth.  Anyone know how dd works?
Brrr.  It gets to RAM after being mmap'ed and linked.  Our VM is
not that broken to allow disk cache swap out binary working on it
-- or I'm completely dumb.

> If dd is RAM resident, more RAM might help?  Are the data transfers
> performed directly or are they buffered in RAM?
Buffered, of course.  With Linux 2.2 and before, even
double-buffered (which is cured in 2.4, thanks God).

> > ...but if hassle is unbearable, "init 1; umount -a; sync; sync; dd"
> > should do the job (although you get root partition copy
> > non-clean in terms of fsck).
> Think I'll stick to the dd transfers since it preserves the partition
> structure well.
Nein -- I'm talking about _what_ data are you copying over.  The
best case is fully-inactive HD (meaning without any mounted
partitions); real-life is "with only root mounted (ro)".

If you're copying "mounted state", you'll get fsck barfing after
first boot (although I've primarily used this method with
journaling fs'es where it's not an issue -- and fsck'ing 40x30Gb
ext2-containing hard drives would be a pain).

> I had been making the hd image copying with dd without any bs
> specification and it worked fine.  Would it be faster if I
> specified bs=1M?
It's block size.  Default one is 512 bytes, and it causes little
too much overhead.  But you can time the execution -- "time dd ...".
dd will allocate that much of memory for buffer, so be careful.
You could probably be better off with 256k or 512k.

> I have read about hdparm in the Config-HOWTO but have not
> yet tried it.
BTW look at Hard-Disk-Upgrade mini-HOWTO and probably Partition
mini-HOWTO, you're going to find much usefult tips there ;-)

> These probably are WD drives.
It affects -m and -X primarily... though I find them extremely
crude at working non-single (block other device or don't work,
which was most annoying with old ones -- 850 to 3.2G in my life).

-- 
 ---- WBR, Michael Shigorin <mike@altlinux.ru>
  ------ http://visa.chem.univ.kiev.ua/~mike/