kern/184154: [cam] QUIRK: SYNC_CACHE not supported on IBM ServeRAID 8k

[info at ITSMexpert.EU]

The following reply was made to PR kern/184154; it has been noted by GNATS.

From: info at ITSMexpert.EU
To: mjacob at freebsd.org, bug-followup at freebsd.org
Cc:  
Subject: Re: kern/184154: [cam] QUIRK: SYNC_CACHE not supported on IBM ServeRAID
 8k
Date: Thu, 28 Nov 2013 00:29:26 +0100

 Just attempt to mount a ZFS pool on six RDM disks caused writing 13 
 error messages for each disk (78 error messages together, five line in 
 dmesg each).
 The mount WAS NOT successful.
 
 ZFS uses SYNC_CACHE quite often (because of its principle), it can lead 
 into significant performance degradation (if mounted).
 
 I can not tolerate such behaviour in production environment handling 
 terabytes of archive data.
 
 I need to upgrade to 10.0 as soon as the STABLE version will be released.
 It seems I will have to patch and recompile kernel first. :-(
 
 On 27/11/2013 23:09, Matthew Jacob wrote:
 > Why do you think this is a serious error? All that the lack of this
 > command support does is cause the driver to be noisy. The device still
 > functions correctly, doesn't it?
 >
 > 10.X is frozen and won't be changed until after release.