<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
mso-fareast-language:EN-US;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.StylE-mailovZprvy17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";
mso-fareast-language:EN-US;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 70.85pt 70.85pt 70.85pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=CS link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hello,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have storage server with OmniOS LTS and 64 GB RAM. This server was installed one year ago. There are about 50 ZVOLs on that server and they are shared through Comstar iSCSI to KVM servers, which are using these ZVOLs for virtual servers.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>After installation, I created a simple Munin script for monitoring ARC and L2ARC, which is using arcstat.pl script from Mike Harsch (http://blog.harschsystems.com/2010/09/08/arcstat-pl-updated-for-l2arc-statistics/). <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Last week, there was realy huge drop in ARC read statistics (you can see that in attachment). On that graph you can see Total ARC accesses per second. The only thing, that we done in that time, was deletion of about 5 unused ZVOLs with many snapshots and some clones. There was no change in virtual servers load. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Is there anyone who have any idea, why deleting some data (ZVOLs and snapshots) have so dramatic efect on ARC accesses? There was more that 60% of free space on that ZFS pool.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thank you!<o:p></o:p></p><p class=MsoNormal>Filip Marvan<o:p></o:p></p></div></body></html>