another error with md malloc based fs

[Michael Schuh]

Hi,

ok i don't know this joke, kbut i know the word's

you have two options option a and option b.

i can't understand how malloc can eat all available
memory, i have 2Gigs of it ;-)
so it seems to me i know what i doing, if
i have 1,6 Gigs free Memory, and i say ok get me 750Megs from
my 1,6 Gigs of free Memory, what was faulty on that????

that would imply for me i can't use my 2 Gigs of ram...
and
<hardliners view>
it also implies that you can put as many ram as you
can find, and you can never use that ram, while a programm
says:" hey guy you are not knowing what you doing......
YOU would use 750Megs of you 24Gigs Ram, no,
you are dumb, you don't use this...."
</hardliners view>

i would use my 2 Gigs of ram, in that way i like :-D
 i would a very fast temporary filesystem in my ram.
not more, not less.....

and the other question is i have a OS that say's i am a release,
and the documentation say you can do this,
who say don't do this?

i have read the thread abaut malloc, but the errors described
are not the same....i have enough ram.....
(so show it to me :-D errare humanum est, is it?)

i hope it gave another way to use such ram-disk without using
swap or other harddisk based backend....otoh my ram is not fully useful
for me and i must, after twelve years of using freebsd, looking back to
linux,
and that i never would, only for using ramdisks....


thanks

regards

michael
2007/3/23, Kevin Oberman <oberman at es.net>:
>
> > Date: Thu, 22 Mar 2007 23:04:16 +0100
> > From: "Michael Schuh" <michael.schuh at gmail.com>
> > Sender: owner-freebsd-stable at freebsd.org
> >
> > Hi,
> > first i have 2GB of RAM, there are be 1,6G free
> > so it should enough toi make the following:
> >
> > # mdconfig -a -t mallo -s 750m -u 0
> > # bsdlabel -w /dev/md0
> > # bsdlabel -e /dev/md0 (create "a" slice to use all free respective
> first 16
> > blocks)
> > # newfs -O2 -U /dev/md0a
> > mount /dev/md0a /mnt
> > # cd to_a_place/with/650MB_of_data/
> > # tar -cf - |( cd /mnt/; tar -xf -)
> > after ~256MB transferred i get following errors, and the system crashes
> > horridble....  first it doesnt react of anything, then it does silently
> > reboot
> > without a shutdown.......leaves all unclean....
> >
> > extract from all.log
> > Mar 22 22:08:14 flying-dutchman kernel:
> > g_vfs_done():md0a[WRITE(offset=686899200
> > , length=131072)]error = 28
> > Mar 22 22:08:14 flying-dutchman kernel:
> > g_vfs_done():md0a[WRITE(offset=687030272
> > , length=131072)]error = 28
> > Mar 22 22:08:14 flying-dutchman kernel:
> > g_vfs_done():md0a[WRITE(offset=687161344
> > , length=131072)]error = 28
> > Mar 22 22:08:14 flying-dutchman kernel:
> > g_vfs_done():md0a[WRITE(offset=687292416
> > , length=131072)]error = 28
> >
> >
> > Any impressions, suggestions or limitations for md with malloc?
> > This errors occures also if i request to reserve the space by
> creation....
> >
> > thanks
> >
> > regards
> >
> > michael
> >
> > --
> > === michael-schuh.net ===
> > Michael Schuh
> > Preußenstr. 13
> > 66111 Saarbrücken
> > phone: 0681/8319664
> > mobil:   0177/9738644
> > @: michael.schuh at gmail.com
>
> Old, old joke:
> Patient: Doctor! It hurts when I do this!
> Doctor: Don't do that.
>
> This is a well known issue with malloc backed md disks. Use swap backed
> ones. They will be the default in V7. They have all of the advantages of
> malloc backed mds without the possibility of eating all available memory
> and crashing the system.
>
> malloc backed md disks are very dangerous and should only be used in
> special circumstances and with great care.
> --
> R. Kevin Oberman, Network Engineer
> Energy Sciences Network (ESnet)
> Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
> E-mail: oberman at es.net                  Phone: +1 510 486-8634
> Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
>
>


-- 
=== michael-schuh.net ===
Michael Schuh
Preußenstr. 13
66111 Saarbrücken
phone: 0681/8319664
mobil:   0177/9738644
@: michael.schuh at gmail.com

=== Ust-ID: DE251072318 ===