On 10.11.2015 20.18, Gordon Messmer wrote:> On 11/10/2015 10:14 AM, Christer Solskogen wrote: >> Queued TRIM seems to be a problem with this kind of drive (with the >> latest firmware), and a "recent" kernel (4.1.x) seems to have this >> fixed this without disabling NCQ completely. Is that patch backported >> to the "mainline" CentOS 6 or CentOS7 kernel? > > Can you provide any references to the specific bug you're referring to?This is the first I found. http://linux.slashdot.org/story/15/07/30/1814200/samsung-finds-fixes-bug-in-linux-trim-code and https://bugs.launchpad.net/ubuntu/+source/fstrim/+bug/1449005 -- chs
We have used that drive for 2 years with no issues. Amazing how much trouble people can get into when they tweak stuff... -Joe -----Original Message----- From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf Of Christer Solskogen Sent: Tuesday, November 10, 2015 03:01 PM To: centos at centos.org Subject: Re: [CentOS] Samsung evo 840 fixes On 10.11.2015 20.18, Gordon Messmer wrote:> On 11/10/2015 10:14 AM, Christer Solskogen wrote: >> Queued TRIM seems to be a problem with this kind of drive (with the >> latest firmware), and a "recent" kernel (4.1.x) seems to have this >> fixed this without disabling NCQ completely. Is that patch backported >> to the "mainline" CentOS 6 or CentOS7 kernel? > > Can you provide any references to the specific bug you're referring to?This is the first I found. http://linux.slashdot.org/story/15/07/30/1814200/samsung-finds-fixes-bug-in-linux-trim-code and https://bugs.launchpad.net/ubuntu/+source/fstrim/+bug/1449005 -- chs _______________________________________________ CentOS mailing list CentOS at centos.org https://lists.centos.org/mailman/listinfo/centos
On 11/10/2015 12:00 PM, Christer Solskogen wrote:> This is the first I found. > http://linux.slashdot.org/story/15/07/30/1814200/samsung-finds-fixes-bug-in-linux-trim-code >That bug isn't specific to Samsung drives. It affected all SSDs used in raid0 and raid10 configurations.> and https://bugs.launchpad.net/ubuntu/+source/fstrim/+bug/1449005That's a different bug, entirely. The bug above was a Linux bug, where this is a drive firmware bug. It's worked around in Linux by blacklisting NCQ TRIM for Samsung's drives. The ATA_HORKAGE_NO_NCQ_TRIM flag was introduced in 3.13. I don't see it in CentOS 7's kernel, so it's almost certainly not in C6 either. You're probably better off disabling NCQ or just testing to see if you need TRIM at all. Particularly if you leave some space unallocated on the drive (TRIM it if you were previously using it), many newer drives manage free blocks very well, and see little or no performance hit for systems that don't use TRIM.