<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="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 11 (filtered medium)">  <style>  </style> </head> <body lang=EN-US link=blue vlink=blue> <div class=Section1> Thanks for the update. I have not followed the thread closely… did you see any significant measured peformance increase in using lvm on a ramdisk?<o:p></o:p> <o:p> </o:p> Regards<o:p></o:p> <o:p> </o:p> <div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'> <div> <div class=MsoNormal align=center style='text-align:center'> <hr size=2 width="100%" align=center tabindex=-1> </div> From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Larry Dickson Sent: 19 May 2008 15:37 To: LVM general discussion and development Subject: Re: [linux-lvm] lvm partition on ramdisk<o:p></o:p> </div> <o:p> </o:p> <div> Final results FYI in this investigation: A recent Ubuntu release gets past the 1TB limit. I found binaries for dosfstools_2.11-2.1ubuntu3 at <a href="http://packages.ubuntu.com/feisty/otherosfs/dosfstools">http://packages.ubuntu.com/feisty/otherosfs/dosfstools</a> and unpacked them with ar -x. The source is in <a href="https://launchpad.net/ubuntu/+source/dosfstools/2.11-2.1ubuntu3">https://launchpad.net/ubuntu/+source/dosfstools/2.11-2.1ubuntu3</a> <o:p></o:p> </div> <div> With 4KB sectors, it defaults to 128KB clusters and reaches over 97% write speed on an 8TB volume. The ramdisk area needed is a little over 512MB, so if you use 768MB you get quite a bit of room for directories also on ramdisk, and with a little finesse you can even make the subdirectories lay themselves down on ramdisk. To be "Windows-legal" you could use 32KB clusters and a little over 2GB ramdisk (or a little over 1GB with one FAT). Linux is happy with the big clusters, and according to the design should actually be willing to go to 16TB. Larry<o:p></o:p> </div> <div> <o:p></o:p> </div> <div> On 5/13/08, Stuart D. Gathman <<a href="mailto:stuart@bmsi.com">stuart@bmsi.com</a>> wrote: <o:p></o:p> On Tue, 13 May 2008, Larry Dickson wrote: > on the full, unpartitioned lv. Then it mounted, with the entire FAT on > ramdisk, and wrote very fast because FAT32 (like DOS) lays down data in > order from the start of a disk and does not skip around (I'd be interested > if anyone knows any other file systems with that property). The SysV filesystem put a fixed size inode table at the beginning of a partition. More modern filesystems from ext to reiser try to distribute the meta-data to keep it closer to the data. This is, of course, counter productive when the beginning of a disk is significantly faster and seek-free as in your setup. Since ext3 inode placement is table driven (with the table in a magic inode), there is probably a simple patch to mke2fs to create only one inode table at the beginning of a drive. In fact, I wonder if there is already an option... looks like -g blocks_per_group might do the trick - assuming inodes are at the beginning of a block group, rather than the middle. If not, a patch to mke2fs is needed to do what you want. -- Stuart D. Gathman <<a href="mailto:stuart@bmsi.com">stuart@bmsi.com</a>> Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154 "Confutatis maledictis, flammis acribus addictis" - background song for a Microsoft sponsored "Where do you want to go from here?" commercial. _______________________________________________ linux-lvm mailing list <a href="mailto:linux-lvm@redhat.com">linux-lvm@redhat.com</a> <a href="https://www.redhat.com/mailman/listinfo/linux-lvm">https://www.redhat.com/mailman/listinfo/linux-lvm</a> read the LVM HOW-TO at <a href="http://tldp.org/HOWTO/LVM-HOWTO/">http://tldp.org/HOWTO/LVM-HOWTO/</a><o:p></o:p> </div> <o:p> </o:p> </div> </div> </body> </html>