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Re: The order of my SATA and PATA are switching all the time



st wrote:
> Stefan Monnier wrote:
> > I see many people suggested UUIDs and other funny long names.  What I
> > use instead: LVM.  This way you get to name the "disks" and
> > "partitions" with meaningful names which only change when you decide
> > to change them.
>
> One simple question, though: if you have 2 similar HDDs and one
> of them starts to fail, how do you know which one it is?

I assume you mean which physical disk is which?

There are useful tools hdparm, smartctl, blkid, lsblk and probably
others too.

  # hdparm -I /dev/sda
  ...
        Model Number:       ST340014A                               
        Serial Number:      5JXC6GK4            

  # smartctl -i /dev/sda
  Model Family:     Seagate Barracuda 7200.7 and 7200.7 Plus family
  Device Model:     ST340014A
  Serial Number:    5JXC6GK4

  # smartctl -l error /dev/sda
  ...
  No Errors Logged

Or it might say that is has logged errors.  In either case you can now
write down the model and serial number of the disk drives both working
and giving errors.  Then when you open the box up to replace it you
will be able to know which one is good and which one is bad.

If you were asking how do you map from lvm names to physical names
then that is through the pvs and pvdisplay commands.

  # pvs
    PV         VG   Fmt  Attr PSize  PFree
    /dev/sda5  vg0  lvm2 a-   36.77g    0 

So for that example vg0 has a single /dev/sda5 partition.  If you are
using raid it will look like this:

  # pvs
    PV         VG   Fmt  Attr PSize   PFree  
    /dev/md1   v1   lvm2 a--  232.83g   8.90g
    /dev/md2   v1   lvm2 a--  298.02g  16.26g
    /dev/md3   v1   lvm2 a--  400.18g 168.89g

Then to map from /dev/mdX devices use mdadm --detail.

  # mdadm --detail /dev/md1
    Number   Major   Minor   RaidDevice State
       0       8        5        0      active sync   /dev/sda5
       1       8       21        1      active sync   /dev/sdb5

Bob

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