RE: Question regarding --backup-file

["Peter Kovari" <peter@kovari.priv.hu>]

> > Hi all,
> >
> > I understand, that a change from RAID5 to RAID6 by adding a single disk
-
> > eg. keeping the number of data disks - requires a backup file throughout
the
> > whole reshape process. For a larger, multi-TB array this means millions
of
> > writes to the backup file, which - if i'm correct - means means millions
of
> > writes to the same physical sectors of the disk that holds the backup
file.
> > Is this not problematic? How many write operations can a typical drive
> > tolerate nowadays? (on the same sectors)

> Lots, where Lots >= 1 and Lots < infinity.

> I've never seen rotating media specify any form of limitation to writes. 
> Have you?

No, that's why i'm asking. 

Imho, in typical usage, write cycle counts on a certain sector may not be
that high, even on a database server. I doubt it ever goes over a few
hundred thousands during the life cycle of the hard disk. On the other hand,
a single reshape on a larger array can trigger tens of millions of write
cycles on certain sectors. Sectors do fail eventually, so I'm wondering if
the "no limit" is truly a no limit, or manufacturers just won't state this
info because in "normal" usage, customers will never reach that limit.

Btw, i'm sure SSD's are not meant to take such a pressure.

Cheers,
Peter