Re: question about prblem with raid 1 for freeBSD

[Damien Fleuriot]

On 6/22/12 11:11 AM, dude golden wrote:
 HI there,
 
 hope my email find you well, i recently order a server with below 
 configuration 
 
 INTEL
 1x Quad-Core i5-2500 3.3GHz, 6M Cache
 16GB DDR3
 2x 500GB SATAII
 
 then ask from my COLOCATION to install FreeBSD 8.2 or 8.3 with RAID 1, after 
 many times of fail in installation from colocation they said that we have 
 problem with RAID 1.we suggest them to play with different kind of RAID like 
 RAID 5 and they said as our requested server only have 2 HDD, its not 
 possible to set up RAID 5.
 
 now they said us that the only way for having backup of DATA in this 
 condition is set up a scheduled task to put back up of data in the second HDD 
 .
 
 
 
 now i really need to know if there is a only way for having data back up in 
 this condition or you have better idea according to your experience.also if 
 its the only way , would it be a good level of data security ?
 
 
 looking forward to hear from your side soon.
 
 Regards,
 
 Smartelcom Team  


Hi,


Your colleagues are correct about the RAID levels, you can only do RAID5
with a minimum of 3 disks.

Your available options with 2 disks are JBOD, RAID0 or RAID1.

You obviously want RAID1.



How have they tried to install the server ?

I've had no problems ever installing 8.2 or 8.3 as a RAID using either
gmirror, or hardware RAID.

Does the server have a hardware RAID controller or are you trying
software RAID ?

Do you have remote console access to the server ?

___
freebsd-questions@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org

Re: question about prblem with raid 1 for freeBSD

[Matthew Seaman]

On 22/06/2012 10:11, dude golden wrote:
 INTEL
 1x Quad-Core i5-2500 3.3GHz, 6M Cache
 16GB DDR3
 2x 500GB SATAII

 then ask from my COLOCATION to install FreeBSD 8.2 or 8.3 with RAID
 1, after many times of fail in installation from colocation they said
 that we have problem with RAID 1.we suggest them to play with
 different kind of RAID like RAID 5 and they said as our requested
 server only have 2 HDD, its not possible to set up RAID 5.

Correct.  RAID5 requires at least 3 drives. The only way to have
resilience against disk failure with just two drives is to use RAID1
(mirroring).

How exactly are your colleagues attempting to set up RAID1.  There are
several different ways of doing it, but these are the most popular:

   * Using the built-in ATAPI RAID provided by many motherboards

   * gmirror

   * ZFS

ATAPI RAID is perhaps the least effective, and may require downtime in
order to rebuild the system after a disk failure.  I suspect this is
what is causing your colleagues problems.

For setting up a gmirror RAID see this article:

  http://onlamp.com/pub/a/bsd/2005/11/10/FreeBSD_Basics.html

(That will work fine with 8.2 or older and the old sysinstall; needs to
be adapted if using the new bsdinstall with gpart)

For setting up a ZFS mirror, see:

  http://wiki.freebsd.org/RootOnZFS/GPTZFSBoot/Mirror

or I wrote a similar piece assuming use of bsdinstall:

  http://www.infracaninophile.co.uk/articles/install-on-zfs/

Both of the gmirror or ZFS procedures involve going beyond what the
installer provides and doing at least part of the work from the command
line.  If that is too scary to contemplate, then try using the PC-BSD
installer to install FreeBSD -- it lets you set up mirrors or ZFS from a
menu system, and can install plain FreeBSD as well as PC-BSD:

  http://www.pcbsd.org/index.php?option=com_zooview=itemItemid=98

 now they said us that the only way for having backup of DATA in this
 condition is set up a scheduled task to put back up of data in the
 second HDD .

Well, this is really unsatisfactory and your colleagues should be ashamed.

First of all, RAID1 is not *backup*.  If you accidentally delete a file,
it will be removed from both of the mirrored drives.  The thing that
RAID1 gets you is resilience to disk failure: one of your drives going
'pop' will not result in the system crashing or any service interruption.

Backup of the system should be arranged through some other means: there
are many programs available to do the job in the base system or the
ports -- personally I like tarsnap, which will backup your data to the
cloud (Amazon flavoured cloud, that is) for a very reasonable rate.

Cheers,

Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.
PGP: http://www.infracaninophile.co.uk/pgpkey





signature.asc
Description: OpenPGP digital signature