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Subject: SSD endurance calculations
From: =?utf-8?Q?Christiaan_Willemsen?= <cwillemsen@technocon.com>
To: =?utf-8?Q?pgsql-performance=40postgresql=2Eorg?=
	<pgsql-performance@postgresql.org>
Date: Mon, 21 Nov 2011 22:03:46 +0100
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Hey there,=0D=0A=0D=0A=C2=A0=0D=0AWe are looking at beefing up our server=
s with SSD's. Some of you did some interesting tests with the Intel 320. =
So the idea came to make a RAID10 with four 600GB models.=0D=0A=0D=0A=C2=A0=
=0D=0AI did however do some calculations with the current database server=
 (220GB database, expected to grow to 1TB by the end of next year). I spe=
cifically looked at /proc/diskstat at the read/write figures. From there =
I could see a read/write ratio of 3:1, and I also saw a wopping 170GB of =
writes per day (for a database that currently grows 1GB per dag). That se=
ems like an insanely high figure to me! How come=3F We do mostly inserts,=
 hardly any updates, virtually no deletes.=0D=0A=0D=0A=C2=A0=0D=0ASecondl=
y, I also looked at the reliability figures of the Intel 320. They show 5=
 years of 20GB per day, meaning that it will hold up for about 200 days i=
n our system. RAID 10 wil make 400 days of that, but this seems hardly a =
lot.. Am I missing something here=3F=0D=0A=0D=0A=C2=A0=0D=0AKind regards,=
=0D=0A=0D=0A=C2=A0=0D=0AChristiaan=0D=0A=0D=0A=C2=A0=0D=0A=C2=A0=0D=0A=C2=
=A0=0D=0A
--=_OOHOvEAaVA3qLQcxFyIK0ZYO0bTA1JFkDxIjO8Khu24HjkAN
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Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://ww=
w.w3.org/TR/html4/loose.dtd"><html>=0A<head>=0A  <meta name=3D"Generator"=
 content=3D"Zarafa WebAccess v7.0.1-28479">=0A  <meta http-equiv=3D"Conte=
nt-Type" content=3D"text/html; charset=3Dutf-8">=0A  <title>SSD endurance=
 calculations</title>=0A  <style type=3D"text/css">=0A      body=0D=0A   =
   {=0D=0A        font-family: Arial, Verdana, Sans-Serif ! important;=0D=
=0A        font-size: 12px;=0D=0A        padding: 5px 5px 5px 5px;=0D=0A =
       margin: 0px;=0D=0A        border-style: none;=0D=0A        backgro=
und-color: #ffffff;=0D=0A      }=0D=0A=0D=0A      p, ul, li=0D=0A      {=0D=
=0A        margin-top: 0px;=0D=0A        margin-bottom: 0px;=0D=0A      }=
=0D=0A  </style>=0A</head>=0A<body>=0A<p>Hey there,</p><p>&nbsp;</p><p>We=
 are looking at beefing up our servers with SSD&#39;s. Some of you did so=
me interesting tests with the Intel 320. So the idea came to make a RAID1=
0 with four 600GB models.</p><p>&nbsp;</p><p>I did however do some calcul=
ations with the current database server (220GB database, expected to grow=
 to 1TB by the end of next year). I specifically looked at /proc/diskstat=
 at the read/write figures. From there I could see a read/write ratio of =
3:1, and I also saw a wopping 170GB of writes per day (for a database tha=
t currently grows 1GB per dag). That seems like an insanely high figure t=
o me! How come=3F We do mostly inserts, hardly any updates, virtually no =
deletes.</p><p>&nbsp;</p><p>Secondly, I also looked at the reliability fi=
gures of the Intel 320. They show 5 years of 20GB per day, meaning that i=
t will hold up for about 200 days in our system. RAID 10 wil make 400 day=
s of that, but this seems hardly a lot.. Am I missing something here=3F</=
p><p>&nbsp;</p><p>Kind regards,</p><p>&nbsp;</p><p>Christiaan</p><div><p =
style=3D"font-family: monospace; ">&nbsp;</p></div><p>&nbsp;</p><p>&nbsp;=
</p>=0A</body>=0A</html>
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