<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
</head>
<body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Hello<o:p></o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span class="apple-style-span"><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">I've submit patch (</span></span><span class="apple-style-span"><span style="font-size: 13.5pt; font-family: Helvetica, sans-serif; "><a href="https://review.openstack.org/#/c/7101/" style="color: blue; text-decoration: underline; ">https://review.openstack.org/#/c/7101/</a></span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">),
that help Swift use special features of file system on that it working.<o:p></o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span class="apple-style-span"><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">One of the changes in this patch is for reduce number of network replicas of partition if user use self-repairing mirrored device. For this user should add mirror_copies
parameter to each device. By default mirror_copies for all devices is 1, so changes of code don't take any effect for current Swift deployments. </span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; "> For almost all systems three singleton
replicas can be replaced by two mirrored replicas. <span class="apple-style-span">So if all user devices is mirrored (mirror_copies >= 2), then number of network copies of most partition will be reduced, and then for operation like PUT and POST we will make
less request. </span>The definition of mirroring specifically requires the local file system detect the bad replica on its own, such as by calculating checksums of the content, and automatically repairing data defects when discovered<span class="apple-style-span">.
So if one of devices fail recovery will be done by file system without coping data from other device. This changes was made in ring builder and take effect if mirror_copies > 1, so this code is not danger for current Swift users, but for other users can provide
new </span>possibility<span class="apple-style-span">.</span><o:p></o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Also this patch add hooks, that can be used for manipulation with file system, when Swift operate with account, container or object files. This hooks used by middleware that is separate project,
so if user don't install it this changes will not take effect.<o:p></o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; ">This feature only enabled by customers </span><span class="apple-style-span"><span style="font-size: 11.5pt; font-family: Calibri, sans-serif; ">that have chosen to install the enabling software
and turn it on and </span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">it is easy to test that this patches have no impact on the generic deployments.<o:p></o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Most of patch code was restructured, most of logic was moved to middleware level and use hooks in Swift code. I create separate project (LFS middleware <a href="https://github.com/nexenta/lfs" style="color: blue; text-decoration: underline; ">https://github.com/nexenta/lfs</a>)
for now there are only 2 supported file system types (XFS and ZFS) there. Also this middleware provide API for getting file system status information (for example, for ZFS it's current pool status, etc).<o:p></o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></span></div>
</div>
<div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Further the Nexenta side-project is not the only local file system that could provide this form of local replication and data protection.Trading off between network replication and local replication
is a valid performance decision. Insisting on a fixed amount of network replication without regard to the degree of local protection provided against data loss would effectively bias the system towards network replication only. Why pay for local data protection
if you cannot reduce the amount you pay for network replication? This patch enables solutions that widen the range of choices available to users as to how they protect their data.<o:p></o:p></span></div>
</div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Thanks,<o:p></o:p></span></div>
</div>
<div>
<div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">
<span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Victor Rodionov</span></div>
</div>
</body>
</html>