Date: Wed, 28 Nov 2012 17:54:42 +0200 From: =?UTF-8?B?TWV0aW4gRMO2xZ9sw7w=?= <metindoslu@gmail.com> To: Sergey Kandaurov <pluknet@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: Performance Difference on UFS and ZFS Message-ID: <CAJOrxZCyshi0rBXpm__b4Qf6gw=fQe1EMsjnukRE-XKxa-_niw@mail.gmail.com> In-Reply-To: <CAE-mSOLcc-USkCZqsiCFsp2SqJ7VPDdkkCHRCxP=8hSg=gAjdw@mail.gmail.com> References: <CAJOrxZCNeo-v_=LT8x1UniRspzZ5qs_DnnOtnb4DnF-RwGFJFw@mail.gmail.com> <CAE-mSOLcc-USkCZqsiCFsp2SqJ7VPDdkkCHRCxP=8hSg=gAjdw@mail.gmail.com>
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Hi Sergey, I tested it on a cc1.4xlarge EC2 instance, here is the specs: 23 GiB of memory 33.5 EC2 Compute Units (2 x Intel Xeon X5570, quad-core =E2=80=9CNehalem=E2= =80=9D architecture) 1690 GB of instance storage 64-bit platform I installed PostgreSQL from its port on FreeBSD. I didn't do any tuning for PostgreSQL or FreeBSD. Data access pattern consists of completely from sequential reads such "select count(*) from table_name". I measured performance with PostgreSQL's timing option. As as side note; all queries are served from memory, so there were no disk usage for these tests. Thanks, Metin On Wed, Nov 28, 2012 at 4:49 PM, Sergey Kandaurov <pluknet@gmail.com> wrote= : > On 28 November 2012 12:35, Metin D=C3=B6=C5=9Fl=C3=BC <metindoslu@gmail.c= om> wrote: >> Hi - >> >> I installed PostgreSQL 9.1.6 on FreeBSD 9.0-RELEASE, and compared ZFS >> to UFS. I also made sure all data easily fit into memory, ran some >> sequential scan queries on the database. >> >> Query run times on UFS were 100-200% slower than those of ZFS. This >> was intriguing as all data came from memory. What could be causing >> such a large performance difference? > > Hi Metin D=C3=B6=C5=9Fl=C3=BC! > > That's interesting. Can you please share your settings? > Hardware configuration, system tuning (sysctl, zfs), PostgreSQL settings, > data access pattern (read/write ratio), and how you measure performance > would be a good start. > > -- > wbr, > pluknet --=20 Metin D=C3=B6=C5=9Fl=C3=BC
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