Hi Hanno, how do you calculate the best ashift value?
Thanks, Steffen -----Original Message----- From: OmniOS-discuss [mailto:omnios-discuss-boun...@lists.omniti.com] On Behalf Of Hanno Hirschberger Sent: Mittwoch, 23. September 2015 14:43 To: omnios-discuss@lists.omniti.com Subject: Re: [OmniOS-discuss] iSCSI poor write performance Hi Martin, On 23.09.2015 10:51, Martin Truhlář wrote: > Tests revealed, that problem is somewhere in disk array itself. are you familiar with the ashift problem on 4k drives? My best guess would be that the 1 TB WD drives are emulating a block size of 512 bytes while using 4k sectors internally. OmniOS is using a ashift value of 9 then to align the data efficiently (on 512 byte sectors!). This slows the whole pool down - I had the same problem before. The ashift value has to be 12 on 4k drives! Try the command 'zdb' to gather the values for your drives. Look for 'ashift: 9' oder 'ashift: 12'. Regards, Hanno _______________________________________________ OmniOS-discuss mailing list OmniOS-discuss@lists.omniti.com http://lists.omniti.com/mailman/listinfo/omnios-discuss _______________________________________________ OmniOS-discuss mailing list OmniOS-discuss@lists.omniti.com http://lists.omniti.com/mailman/listinfo/omnios-discuss