mirror

[Furnish, Trever G]

Don't know anything about that particular hardware, but it looks like it
has a hardware raid controller -- can't you just mirror using that?  If
so, that'll be your best performance choice.  The only headache there is
that you will also need some mechanism for knowing when drives behind
the raid controller fail, which usually means you're out of luck unless
the vendor has released Linux tools to notify you of that stuff.  HP
provides such tools for all of their supported hardware, no clue about
IBM.

You didn't mention the version of Linux you're using either.  The
mirroring choices available differ depending on version.  In RHEL3 it's
pretty much just md or some commercial package as your choice, unless
you want to replace lvm with lvm2 or evfs.  Md works fine.  In RHEL4 and
RHEL5 you have lvm2 with mirroring as a choice, although for all I know
it may still just be implemented via md.  Mirroring the entire disk
(including /, /boot, and /bin) can be done with md, not sure about the
other tools (probably can be done with them too though).

Some links:
http://fy.chalmers.se/~appro/linux/HOWTO-mirror-root.html
http://www.jukie.net/~bart/blog/20060410220525


> -----Original Message-----
> From: redhat-list-bounces at redhat.com 
> [mailto:redhat-list-bounces at redhat.com] On Behalf Of Mad Unix
> Sent: Thursday, May 17, 2007 6:08 AM
> To: General Red Hat Linux discussion list
> Subject: mirror
> 
> am looking to mirror my internal disk to another disk located 
> on the machine test at linuxppc:~> df -kh
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/sda3             131G  8.4G  116G   7% /
> /dev/sda2              31M  8.9M   20M  31% /boot
> none                  930M     0  930M   0% /dev/shm
> 
> my dmesg
> ----//-------------------
> SCSI subsystem initialized
> ipr: IBM Power RAID SCSI Device Driver version: 2.0.11.2 
> (January 24, 2006) ipr 0000:d0:01.0: Found IOA with IRQ: 325 
> ipr 0000:d0:01.0: Starting IOA initialization sequence.
> ipr 0000:d0:01.0: Adapter firmware version: 0510005E ipr 
> 0000:d0:01.0: IOA initialized.
> scsi0 : IBM 573E Storage Adapter
>   Vendor: IBM   H0  Model: HUS151414VL3800   Rev: S430
>   Type:   Direct-Access                      ANSI SCSI revision: 04
> SCSI device sda: 286748000 512-byte hdwr sectors (146815 MB) 
> SCSI device sda: drive cache: write through SCSI device sda: 
> 286748000 512-byte hdwr sectors (146815 MB) SCSI device sda: 
> drive cache: write through
>  sda: sda1 sda2 sda3 sda4 < sda5 >
> Attached scsi disk sda at scsi0, channel 1, id 5, lun 0
>   Vendor: IBM       Model: VSBPD4E2  U4SCSI  Rev: 7217
>   Type:   Enclosure                          ANSI SCSI revision: 02
> scsi: unknown device type 31
>   Vendor: IBM       Model: 573E001           Rev: 0150
>   Type:   Unknown                            ANSI SCSI revision: 00
> ----------------------//-----
> 
> How would you do the mirror?
> --
> madunix
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