Michael ODonnell writes: > > > OK, the ramdisk story is looking a bit better now. > > First, the tmpfs trick is definitely cool and worth remembering > but isn't what we're looking for because some of what makes it > cool also makes it unsuitable for our purposes. In particular, > tmpfs has close ties to the kernel's buffer cache so files > in tmpfs may actually be on backing store and since we're > investigating a ramdisk solution to get some low-latency > characteristics that makes tmpfs unsuitable for our purpose. > Too bad, because rigging tmpfs is easier than rigging a ramdisk. > > The key to getting the [EMAIL PROTECTED]@!!! ramdisk to be usable was > figuring > out that ext2 and the ramdisk device driver had to agree on > block size. The default for ramdisk is 1k and the default for > ext2 is 4k. At first I tried to specify ramdisk_size=1048576 > and ramdisk_blocksize=4096 on the kernel commandline (units are > Kb for the former and bytes for the latter) and all would have > been well..... except that the machine in question boots from an > initrd and the ext2 filesystem therein was already specified as > using 1k blocks and the kernel panic'd when it failed to mount > the initrd due to that mismatch. > > So, since I don't feel like rebuilding the initrd's filesystem > with 4k blocksize I had the ramdisk fall back to the default 1k > and told mkfs.ext2 to build the filesystem in the ramdisk using > a 1k blocksize, thus: > > dd if=/dev/zero bs=1024k count=1048576 of=/dev/ram9 > mkfs.ext2 -b 1024 /dev/ram9 > mount /dev/ram9 /mnt/test
If you're using a ramdisk for purposes other than booting, make sure you have backported this fix if you are running a kernel older than 2.6.24: if you don't, your ramdisk blocks will disapear once you use all the ram in the system and the kernel needs to free memory http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5d0360ee96a5ef953dbea45873c2a8c87e77d59b -- Dave _______________________________________________ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
