<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 12 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>All,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am in the process of designing a production datacenter storage grid. It will start at 4x4TB storage nodes, and hopefully grow to 10x4TB before too long. It will store a variety of content, but mostly images under 4MB. There are apt to be tens of millions of files almost immediately, as the day-one user will be moving existing data off of a NFS solution. ‘Put’ access will be via the FTP frontend, and ‘get’ access will be via a caching reverse proxy which will frontend the twisted WUI. Directories will probably not go more than 3 deep.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The grid will never grow to more than 10 nodes, as we’ll just create additional grids after that (this is primary to prevent an A-M-D type failure where dircaps are spread over many servers). If more space is required, we’ll expand the 10 nodes, rather than add more nodes. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>At some point, we plan to use rsync to create a ‘replica grid’ off-site. Expiration will be turned on, and renewal scripts will crawl the user directories to keep leases current.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Since nodes will never leave the grid permanently (only brief windows for reboots and such), I was thinking that simple replication (k=1, n=2, happy=2) would be sufficient. The backing disks are in RAID-1, to prevent a disk failure from requiring a file repair.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Are there any initial concerns with this design? Will Tahoe scale to this many files? Is there any problem with replication-only on a server grid? Is there a better way to replicate the grid than rsyncing the master nodes to a slave node in a remote facility (for example, is it perhaps possible to make the FTP frontend ‘put’ to two grids instead of just one)?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Lastly, is there any method for accounting/logging on the FTP server? For example, when a user uploads a file, is it possible to have a log that says what time, what user, what file, and how much data?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Sorry for all the questions!<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Nathan Eisenberg<o:p></o:p></p></div></body></html>