software (scsi) raid 1

software (scsi) raid 1

Post by bluuur » Sat, 07 Jun 2003 22:16:39



i have a 4.8-release system with several scsi disks.

the system is running as a samba fileserver (and sshd).
root disk is the first scsi disk, 2gb.
data is the last disk (#7 at the moment).
everything is up and running fine.

problem: i don't trust my root disk, so i was hoping to use another
2gb disk (the same make and size) to set up a raid-1 system. i don't
need extra speed, just mirroring.

[of corse you think, just buy another disk! my system is in a home
network, and i'd sooner spend the cash on something else.... (scsi
disks are quite expensive a poor student), also 2gb disks are
impossible to find new]

unfortunatly i have read in several places that raid-x should not be
used for the root disk.

[does this include raid-1? if so, why? all i should do is mirror....]

can any one think up a way to get my system reliable? i was thing
maybe making a cron job to dump eveything to the second disk might
work, but i would prefer a raid-1 for much more instant mirroring.

if i do choose to dump through a cron job and disk 1 dies, would i be
able to disconect disk 1 and boot from disk 2 (i surpose not, but
asking doesn't hurt).

greets
a

 
 
 

software (scsi) raid 1

Post by Lowell Gilber » Sun, 08 Jun 2003 05:17:24


comp.unix.bsd.freebsd is not widely propagated, so you won't
necessarily get much help here (in comp.unix.bsd.freebsd).
See http://www.freebsd.org/support.html for better ideas...
[followups redirected accordingly]


> can any one think up a way to get my system reliable? i was thing
> maybe making a cron job to dump eveything to the second disk might
> work, but i would prefer a raid-1 for much more instant mirroring.

It depends on what you need to be protected from.  For most people on
a home setup, just doing more frequent backups (and keeping some of
them offsite) is more important than anything they could do with
RAID.  If you're expecting your main disk to die, then you should use
the other disk as your primary, and stop depending on the one you
think is on its way out.

Quote:> if i do choose to dump through a cron job and disk 1 dies, would i be
> able to disconect disk 1 and boot from disk 2 (i surpose not, but
> asking doesn't hurt).

You could do the backup in ways that could make this more likely to
work.  With rdist, for example, or even dump and restore...

 
 
 

software (scsi) raid 1

Post by bluuur » Wed, 11 Jun 2003 21:53:26



Quote:> It depends on what you need to be protected from.  For most people on
> a home setup, just doing more frequent backups (and keeping some of
> them offsite) is more important than anything they could do with
> RAID.  If you're expecting your main disk to die, then you should use
> the other disk as your primary, and stop depending on the one you
> think is on its way out.

ah, but my data is more important. last friday one disk died (at
least, i think so), and i was able to reinstall the system from
scratch in just under 90 minutes. so even in a worst case (eg, disk
dies) i still have everything up and running pretty fast.

Quote:> > if i do choose to dump through a cron job and disk 1 dies, would i be
> > able to disconect disk 1 and boot from disk 2 (i surpose not, but
> > asking doesn't hurt).

> You could do the backup in ways that could make this more likely to
> work.  With rdist, for example, or even dump and restore...

yes, well i expecteds to get a response like this. i haven't rtfm on
dump-restore yet, but i assume it should not be run on a (multi-user)
running system. that's why i'd prefer a raid-1 system.

also, seeing as it's only a home-network and i want to get experienced
(with freebsd, that is), i have to 'think up' neccisary upgrades to
the system. thus raid.

so, to get back to the main question, can i set up a raid-1 system
with my sys-disk? concerning this i did rtfm, but it isn't very clear
about raid-1 and system disks (all other raids are not advised).

 
 
 

software (scsi) raid 1

Post by Lowell Gilber » Thu, 12 Jun 2003 03:39:24


As I advised you the first time, this newsgroup is what's
(technically) known as "bogus," and very few people ever
see it.


> so, to get back to the main question, can i set up a raid-1 system
> with my sys-disk? concerning this i did rtfm, but it isn't very clear
> about raid-1 and system disks (all other raids are not advised).

What FM did you read?  The FreeBSD Handbook has a whole section titled
"Using Vinum for the root filesystem"...
 
 
 

software (scsi) raid 1

Post by bluuur » Thu, 12 Jun 2003 20:28:05



> As I advised you the first time, this newsgroup is what's
> (technically) known as "bogus," and very few people ever
> see it.

hmmm, i had a look at the link in you first reply, which lead to the
well known freebsd.org site. there they point to here.... which other
interactive support do you suggest? i'm not to happy with the mailing
list (i've been subscribing foor quite a while now), as i can't seem
to be able to post anything.... bummer.


> > so, to get back to the main question, can i set up a raid-1 system
> > with my sys-disk? concerning this i did rtfm, but it isn't very clear
> > about raid-1 and system disks (all other raids are not advised).

> What FM did you read?  The FreeBSD Handbook has a whole section titled
> "Using Vinum for the root filesystem"...

which i read, but looking over it again it seems an extra chapter
suddenly appeared (13.9 Using Vinum for the root filesystem), which i
hadn't noticed before...  (or did the freebsd team see my post and
decide to wright another chapter? erm, nah.) maybe i should
rt-whole-fm in future.

as it says in the chapter title, this is for the root file system, but
i want to raid-1 the entire 2gb disk (with /, /usr, /var and the like)
to another 2gb disk. this quote:

"The root volume must not contain more than one concatenated subdisk
per plex."

puts me off a bit, does this mean i could only raid the root
partition? what if the rest is mounted into root? i guess that doesn't
make any differance, as it's not mounted until later....

i can't seem to find what a concatenated subdisk is in the handbook,
and i thus don't know if it will affect me....

 
 
 

software (scsi) raid 1

Post by bluuur » Fri, 13 Jun 2003 19:35:49


aal my problems solved:

in a fit of madness i *ed half the internals of my system out of a
sixth story apartment window, unfortunatly causing substantial damage
to a parked car below... it seems bmw cars are not scsi disk
compatable....

 
 
 

software (scsi) raid 1

Post by Lowell Gilber » Fri, 13 Jun 2003 21:02:31



> in a fit of madness i *ed half the internals of my system out of a
> sixth story apartment window, unfortunatly causing substantial damage
> to a parked car below... it seems bmw cars are not scsi disk
> compatable....

It turns out that SCSI drives are being improved every year to handle
higher radial velocities, but their capacity for linear acceleration
is hardly changing at all.