From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Goryachev Subject: Re: RAID performance Date: Fri, 08 Feb 2013 11:00:03 +1100 Message-ID: <4c6136c9-4deb-4baf-a861-ca562bbf1ecb@email.android.com> References: <51134E43.7090508@websitemanagers.com.au> <51137FB8.6060003@websitemanagers.com.au> <51139799.2070004@fnarfbargle.com> <51139FEE.3020807@websitemanagers.com.au> <5113E06B.7030808@wirebound.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <5113E06B.7030808@wirebound.net> Sender: linux-raid-owner@vger.kernel.org To: Fredrik Lindgren Cc: Brad Campbell , linux-raid@vger.kernel.org List-Id: linux-raid.ids Fredrik Lindgren wrote: >Hello, > >On 02/07/2013 01:37 PM, Adam Goryachev wrote: >> On 07/02/13 23:01, Brad Campbell wrote: >>> On 07/02/13 18:19, Adam Goryachev wrote: >> BTW, I just created a small LV (15G) and ran a couple of write tests >> (well, not proper one, but at least you get some idea how bad things >are). >> dd if=/dev/zero of=/dev/vg0/testlv oflag=direct bs=16k count=50k >> ^C50695+0 records in >> 50695+0 records out >> 830586880 bytes (831 MB) copied, 99.4635 s, 8.4 MB/s >> > From the iostat output it seems quite clear that the culprit is the >drbd2 device. The /dev/sd[b-f] seems to have plenty more to give, >even though they're doing some 1400 iops each (which seems a >lot for the throughput you're seeing, why are the IOs towards the >physical disks so small?). > >Regarding that drbd device, Is there some mirroring being done to >another machine by way of drbd? If so, with a sync-mirror to another >machine over the network 8,4Mb/s could be quite "normal", right? Thank you for the smack, I realise now that I was stupidly doing this late at night, and as you suggested, the secondary comes online after business hours. I will need to redo my test after manually disconnecting the secondary server after hours. Please ignore the above data, I will re-test tonight and advise. Regards, Adam -- Adam Goryachev Website Managers www.websitemanagers.com.au