<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Mar 31, 2017 at 4:03 PM, Bipin Kunal <span dir="ltr"><<a href="mailto:bkunal@redhat.com" target="_blank">bkunal@redhat.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div><div><div>Hello,<br><br></div><div>Can someone explain me the importance of "direct-io-mode"? </div><div> What I understand is enabling "direct-io-mode" will use FUSE cache and bypass kernel/page cache.</div><div><br></div><div>Will it be beneficial to enable "direct-io-mode" or it will have adverse effect when there is very small files workload such as dovecot and other mail boxes.</div><div>As use case here is of mail boxes, it will be write once and mostly read once.</div><span class="gmail-m_-5965548326003654818HOEnZb"><font color="#888888"><div><br></div></font></span></div></div></div></div></div></div></div></blockquote><div><br></div><div>Mailbox workload involves mainly 2 major posix semantics. <br><br>1. Locking <br></div><div>2. Dependency on rename().<br><br></div><div>And later the challenge of small files.<br><br></div><div>In distributed systems both 1 and 2 mentioned above are harder problem to achieve without performance compromise (ref: CAP). This makes it harder problem to solve for GlusterFS usecase.<br><br></div><div>Well, I am hopeful of already proposed gfid based hashing in DHT-next algorithm to solve some of it, along with few locking enhancements people are planning by GlusterFS 4.0 timeframe, we can revisit this usecase.<br><br></div><div>For the historic nostalgia, I went through the logs to figure out when did anyone first tried mailbox related workload with glusterfs, and seems 2008 is the answer [1] :-)<br></div><div> <br></div><div>Regards,<br></div><div>Amar<br><br>[1] - <a href="http://savannah.nongnu.org/bugs/?24551">http://savannah.nongnu.org/bugs/?24551</a><br><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div><div><span class="gmail-m_-5965548326003654818HOEnZb"><font color="#888888"><div></div></font></span></div></div></div></div></div></div><span class="gmail-m_-5965548326003654818HOEnZb"><font color="#888888"><div><br></div>-- <div>Thanks,<br><div class="gmail-m_-5965548326003654818m_8984869453217818902gmail_signature"><div dir="ltr"><div class="gmail-m_-5965548326003654818m_8984869453217818902gmail_signature"><p class="gmail-m_-5965548326003654818m_8984869453217818902fullname-container" style="box-sizing:border-box;color:rgb(0,0,0);font-family:overpass,sans-serif;font-weight:bold;margin:0px;padding:0px;font-size:14px;text-transform:uppercase">Bipin Kunal</p></div></div></div>
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