[CentOS] LSI MegaRAID experience...

Fri Jul 19 13:55:48 UTC 2013
m.roth at 5-cent.us <m.roth at 5-cent.us>

John Doe wrote:
> From: Drew Weaver <drew.weaver at thenap.com>
>
>> If these drives do not have TLER do not use them with LSI controllers.
>
> Not sure about TLER on those Plextors...
<snip>
TLER would only show up on something that looks at a *very* low level on
the physical drive. What I know is that you can see it with smartctl -
from the man page:  scterc[,READTIME,WRITETIME]  -  [ATA  only]  prints 
values  and
              descriptions of the SCT Error Recovery Control  settings. 
These
              are  equivalent  to  TLER (as used by Western Digital), CCTL
(as
              used by Samsung and Hitachi) and ERC (as used by Seagate).
READ-
              TIME  and  WRITETIME  arguments  (deciseconds) set the
specified
              values. Values of 0 disable the feature, other values less 
than
              65  are probably not supported. For RAID configurations,
this is
              typically set to 70,70 deciseconds.

Note that knowing this was the result of a *lot* of research a couple-or
so years ago. One *good* thing *seems* to be WD's new Red line, which is
targeted toward NAS, they say... because they've put TLER back to
something appropriate, like 7 sec or so, where it was 2 *minutes* for
their "desktop" drives, and they disallowed changing it in firmware around
'09, and the other OEMs followed suit. What makes Red good, if they work,
is that they're only about one-third more than the low-cost drives, where
the "server-grade" drives are 2-3 *times* the cost (look at the price of
Seagate Constellations, for example).

          mark