[Discuss] SSD drives vs. Mechanical drives

[dsr at randomstring.org (Dan Ritter)]

On Wed, May 07, 2014 at 01:56:29PM +0000, Edward Ned Harvey (blu) wrote:
> Seriously dude?
> 
> In software (btrfs and zfs) you should periodically scrub.  In fact, this is something that would be good on *all* raid sets, it's just not available on hardware raid.  What a scrub does is this:  It reads all redundant copies, of all data, on all devices.  Searching for cksum failures anywhere in the storage.  Attempts to correct them as described above.

Seriously dude?

3Ware tw_cli man page:

 Verify activity attempts to verify all units based on their unit
 type. Verifying RAID-1 involves checking that both drives contain the
 exact data. On RAID-5, the parity information is used to verify data
 integrity. RAID-10 and 50 are composite types and follow their respective
 array types. On the 9000 series, non-redundant units such as RAID-0,
 JBOD, single, and spare, are also verified (by reading and reporting
 un-readable sectors).

LSI megacli:

 Patrol read
 Patrol read is a feature which tries to discover disk error
 before it is too late and data is lost. By default it is done
 automatically (with a delay of 168 hours between different
 patrol reads) and will take up to 30% of IO resources.

 To see information about the patrol read state and the delay
 between patrol read runs:
  ...

So, yes, many HW RAID controllers can do this at a block level.

I find your exasperated tone exasperating, by the way. 

-dsr-