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Hi all,

I understand, that a change from RAID5 to RAID6 by adding a single disk

-

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eg. keeping the number of data disks - requires a backup file throughout

the

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whole reshape process. For a larger, multi-TB array this means millions

of

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writes to the backup file, which - if i'm correct - means means millions

of

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writes to the same physical sectors of the disk that holds the backup

file.

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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