FreeBSD + ZFS on a production server?

[Karl Vogel]

>> On Mon, 9 Jun 2008 23:31:35 +0200 (CEST), 
>> Wojciech Puchar <wojtek at wojtek.tensor.gdynia.pl> said:

W> but why you need [a filesystem for linux that do checksum on the fly]?! all
W> PATA/SATA drives do checksumming on every read.  in hardware, no CPU load.

   These days, hardware isn't just hardware.  A disk drive can have around
   300,000 lines of low-level firmware, and who wants to bet that it's
   completely bug-free?  Silent-write errors are actually a big problem:

   http://www.usenix.org/publications/login/2008-06/openpdfs/bairavasundaram.pdf
   An Analysis of Data Corruption in the Storage Stack

   "In this paper, we present the first large-scale study of data corruption.
   We analyze corruption instances recorded in production storage systems
   containing a total of 1.53 million disk drives, over a period of 41 months.
   We study three classes of corruption: checksum mismatches, identity
   discrepancies, and parity inconsistencies.  We focus on checksum mismatches
   since they occur the most; more than 400,000 instances of checksum
   mismatches over the 41-month period."
   
-- 
Karl Vogel                      I don't speak for the USAF or my company

Mangled song lyric: Looks like tomatoes
Actual lyric: Looks like we made it.  (Barry Mannilow)