[SunHELP] Discrepancy in size of stripe and soft partition in SVM

Paul Walsh Paul.Walsh at bcu.ac.uk
Mon Dec 3 07:47:46 CST 2007

Paul Walsh wrote:
> System: SunFire V490, 2 x 146Gb disks + 200Gb LUN on EMC Clariion
> O/S: Solaris 9
> I have a metadevice (d53) which was originally a two-way mirror of 20Gb devices on the internal disks, to which I added
> a 32Gb device from the SAN disk (with the intention of syncing the data then breaking the mirror before redefining it
> using the SAN disk first):


After a bit of digging around I think I've found the cause.  If the number of blocks in a soft partition is divisible by
the number of blocks per cylinder for a particular disk geometry, the size of the stripe (in blocks) will be the same as
that of the soft partition.  If, however, the soft partition doesn't occupy an exact number of cylinders, the size of
the strip gets rounded down.

Due to the difference in geometry of the SAN disk:
* Dimensions:
*     512 bytes/sector
*      32 sectors/track
*     256 tracks/cylinder
*    8192 sectors/cylinder
*   51200 cylinders
*   51198 accessible cylinders

Compared to that of the internal disk of the V490:

* Dimensions:
*     512 bytes/sector
*     848 sectors/track
*      24 tracks/cylinder
*   20352 sectors/cylinder
*   14089 cylinders
*   14087 accessible cylinders

I'll always have a difference in size between stripes on the LUN and stripes on internal disks. :(

Paul Walsh

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