On Mon, Oct 20, 2014 at 2:36 PM, Schweiss, Chip via smartos-discuss < [email protected]> wrote:
> The 840 EVO does NOT have cache power protection and is useless as a log > device. > > Every write to them will be given a cache flush, which will be honored by > the Samsung SSD and flush the cache. This tremendously slows them down > because they get great advantages by caching all their writes. You will > also kill them in rapid fashion because you are forcing many read modify > writes on a TLC SSD. > > You can override this in the sd.conf, but in that case you might as well > use sync=disabled at the zfs level and skip the ZIL all together, because > the 840 EVO is NOT going to have the logs you just sent to them in a power > failure. > > The 840 EVO is a great cache device, but not a log device. You need a > write oriented SSD with power loss protection such as the Intel DC S3700 or > ZeusRAM. > > If all you want is performance at the expense of power loss protection, > just shut off the ZIL with the sync=disabled parameter. This will be > faster than even a bunch of ZeusRAMs as log devices. > Hi Chip & Ian, Thanks, you have convinced me that it is a good idea to move away from the EVO's as log dev's. Apologies to the list for previous top post. Thanks and regards, Andre -- Andre Sachs CloudAfrica t: 076 333 1883 ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
