Messages in this thread | | | Date | Sat, 02 Feb 2008 15:40:36 +0100 | From | devzero@web ... | Subject | Re: [PATCH] Allow NBD to be used locally |
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>In fact, VMware uses local nbd today for its vmware-loop helper >utility, most likely because of the above-mentioned reasons. (Though >it quite often hung last time I tried.)
seems this will go away. recent vmware versions (e.g. server 2.0 beta) have a fuse based replacement for that.
ldd /usr/bin/vmware-mount linux-gate.so.1 => (0xffffe000) libz.so.1 => /lib/libz.so.1 (0xb7f95000) ! -> libfuse.so.2 => /lib/libfuse.so.2 (0xb7f79000) libpthread.so.0 => /lib/libpthread.so.0 (0xb7f61000) libdl.so.2 => /lib/libdl.so.2 (0xb7f5d000) libc.so.6 => /lib/libc.so.6 (0xb7e1c000) /lib/ld-linux.so.2 (0xb7fbd000) librt.so.1 => /lib/librt.so.1 (0xb7e13000)
i`m not sure if this is the perfect approach (slower....) , but at least that shouldn`t have those stability issues as the nbd one.
i always felt uncomfortable with the nbd approach...that`s why i started the following discussion-thread: http://communities.vmware.com/message/854746
anyway, i can see a point to use nbd locally, but i think it shouldn`t be abused for mapping local disk-images of any kind, even if this has better capabilities than loop or other. why should local disk data be sent trough the network layer? isn`t device-mapper the better infrastructure here?
>So what we have is non-linearity -- LBA 22 comes after LBA 40 -- loop >does not deal with that. maybe dm-loop does? http://sources.redhat.com/lvm2/wiki/DMLoop
regards roland
>On Feb 2 2008 12:23, Pavel Machek wrote: >>On Fri 2008-02-01 14:25:32, Laurent Vivier wrote: >>> This patch allows Network Block Device to be mounted locally. >> >>What is local nbd good for? Use loop instead... > >Local NBD is good for when the content you want to make available >through the block device is dynamic (generated on-the-fly), >non-linear or supersparse. > >Take for example VMware virtual disks. Just a guess, but >they roughly can look like this: > > kilobytes 0.. 1: header > kilobytes 1..10: correspond to LBA 0..20 > kilobytes 11..20: correspond to LBA 40..60 > kilobytes 21..22: correspond to LBA 22..23 > >So what we have is non-linearity -- LBA 22 comes after LBA 40 -- loop >does not deal with that. > >And there is supersparsity -- the VMDK file itself is complete, but >unallocated regions like LBA 24..40 are sparse/zero when projected >onto a file/block device, respectively; loop cannot deal with that >either. > >In fact, VMware uses local nbd today for its vmware-loop helper >utility, most likely because of the above-mentioned reasons. (Though >it quite often hung last time I tried.) _____________________________________________________________________ Der WEB.DE SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! http://smartsurfer.web.de/?mc=100071&distributionid=000000000066
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