On Tue, Jan 4, 2011 at 2:09 PM, John Robinson <john.robinson@xxxxxxxxxxxxxxxx> wrote: > > First up, booting. You'll have to boot off a bare device which may in fact > be a mirror over 2 or more sticks. Make that your first partition. I think > it's simpler to make it over all 4. Look up booting from RAID to find out > how. I should have read this more carefully. I performed a full install to a raid0 only to find it incapable of setting up grub. It simply told me there was a fatal error. :-/ It took me a bit more research before the reality of your comment sunk in. So I proceeded again and tried to use the first 100MB of each stick to create a 4 device raid1. For some reason, the partitioning S/W (Ubuntu 10.04.1 server) didn't like that and just hung when it tried to discover the disks. Repeatedly. I finally worked around that by deleting the 100 MB partitions on three of the four drives and just using the first 100 MB on one of the drives for a /boot partition. I completed the installation but the system hung on boot. It just provides a blank screen. Experimenting with the installation USB drive, it seemed to me that I couldn't even boot that with all five thumb drives installed. I scaled back to installation three USB drives, install media on a fourth. I also figured out which slot I needed to put the install media in so as to boot. The BIOS - or perhaps some stage in the boot process - gets confused otherwise. I've booted a live CD and tried running grub-install from a chroot with the /boot and / file systems and the command concluded w/out any errors or warnings. But the system still will not boot. I'm not sure if this is a grub or a RAID problem or some combination. Is there something I need to include with grub when the root file system is on a RAID0? > Then, as far as I know USB flash sticks have lousy or no wear-levelling > algorithms and use cheap flash which may not have very many write cycles, so > given that, I'd either: Time will tell. I plan to move active directories like /var/log and /tmp to tmpfs to reduce writes to the USB sticks. The ones I got, though inexpensive, are from a reputable manufacturer (Mushkin.) Hopefully they have decent wear leveling. Certainly my benchmarks produced irregular results which I suspect were a result of wear leveling delaying writes. > > 1. Use RAID-1, 5 or 10 for the rest of the system with ext4 as you suggest, > > or 2. Use btrfs for the rest of the system - btrfs is included in Ubuntu > 10.10 but you may be able to get it for 10.04. > > And in either case, make sure there are regular backups of the whole lot to > your main disc-based array, because those $7 USB sticks could still give you > problems. Well... As long as I have the install media and capture any customization to backup I should be OK. > > Or 3. I might just decide to use just one stick to boot the system from (as > a /boot) and put the rest of the system in an LVM LV, or even a file, on the > main array, and make sure I had a second stick to start the system from if > the first one went bad. I could do something like that. However I don't care to mess with the main array (the two spinning drives) as recovery of those takes a while. I could just install to a single USB (no RAID) and try to migrate the / to a RAID once I'm off the install media. I could run from the single stick (as Steven Haigh) suggested, but I'd like to take advantage of the speed gains from a RAID0. I could also use 'debirf' as suggested by Iordan Iordanov, but I prefer to retain the full (disk based) environment with ease of installing and updating S/W. I haven't studied debirf but I suspect I would have to create and install a new image any time I want to update or install new packages. Suggestions on how to solve the boot problem would be welcome! thanks, hank -- '03 BMW F650CS - hers '98 Dakar K12RS - "BABY K" grew up. '93 R100R w/ Velorex 700 (MBD starts...) '95 Miata - "OUR LC" polish visor: apply squashed bugs, rinse, repeat Beautiful Sunny Winfield, Illinois -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
