(in the meanwhile, I've gone and made a Linux software-RAID5 box in the
lab to play with)
On Fri, 2003-04-11 at 12:26, Christian Guggenberger wrote:
> > "block units" and then in "bytes." So if I have made a RAID volume with
> > 64K stripes, should I specify a su value of 128? (128*512 = 64K)
> >
>
> no, su=64k _or_ sunit=128 !
> > data disks in a RAID device." So I take this to mean that if I have 8
> > disks in a RAID5, my "sw" parameter is "8"?
> >
>
> having an 8 disk RAID5, you'll need swidth=(8-1)*sunit (=896 for your
> example) - if I remember some
> posts about that topic correctly.( a 8 disk RAID5 has 7 "data" disks in that
> term)
It gets even more confusing when I do:
# mkfs -d sunit=128,swidth=384 /dev/md4
on software RAID5 with 4 disks and 64k stripes, and the status screen
displays:
data = bsize=4096 blocks=84286944,
imaxpct=25
= sunit=16 swidth=48 blks,
unwritten=0
since it apparently displays the "sunit" and "swidth" values in terms of
XFS blocks, which are 4096 bytes each....
Thankfully, "mkfs.xfs" with no options Just Does The Right Thing on this
machine, and sets sunit and swidth correctly when it makes the
filesystem. :) (Though it might be different with hardware RAID...)
--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
#!/usr/bin/perl -w
$_='while(read+STDIN,$_,2048){$a=29;$b=73;$c=142;$t=255;@t=map
{$_%16or$t^=$c^=($m=(11,10,116,100,11,122,20,100)[$_/16%8])&110;
$t^=(72,@z=(64,72,$a^=12*($_%16-2?0:$m&17)),$b^=$_%64?12:0,@z)
[$_%8]}(16..271);if((@a=unx"C*",$_)[20]&48){$h=5;$_=unxb24,join
"",@b=map{xB8,unxb8,chr($_^$a[--$h+84])}@ARGV;s/...$/1$&/;$d=
unxV,xb25,$_;$e=256|(ord$b[4])<<9|ord$b[3];$d=$d>>8^($f=$t&($d
>>12^$d>>4^$d^$d/8))<<17,$e=$e>>8^($t&($g=($q=$e>>14&7^$e)^$q*
8^$q<<6))<<9,$_=$t[$_]^(($h>>=8)+=$f+(~$g&$t))for@a[128..$#a]}
print+x"C*",@a}';s/x/pack+/g;eval
usage: qrpff 153 2 8 105 225 < /mnt/dvd/VOB_FILENAME \
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