Fr David Ousley said the following on 02/22/2011 05:20 PM:
I'm installing Opensuse 11.3 on a new machine. It has an SSD drive, and two RAID 1 (mirrored) hard drives. I was planning to put the /boot and /swap on the SSD for speed (unless you experts -- which I am not -- tell me that that's not a good idea), and the other partitions on the RAID hard drives. I cannot see in the installation Expert Partitioner how to move the /boot and /swap to the SSD. I can shrink the Windows partition on the SSD, so there is 20 GB available, and the proposed partition has 2 GB swap and 700 MB for /boot. So there should be room.
I'm working with a group that is doing things with lots of SSDs and involving Linux, but I'm NDA'd on specifics, so the following is intelligent, informed observations. SSDs are not like normal storage in many ways. Ultimately they "wear out" with traffic and the way they work is very much NOT suited to the way our present crop of file systems are designed. All this is well documented and you can google for details. Putting /boot on the SSD will give you fast booting. Once booted there should be little traffic to that file system. That may be a good thing or a bad thing. However it seems a waste of 'fast store' to me. I'm very sceptical about putting /swap on the SSD. Either you don't need swap or its going to produce the kind of traffic that the SSD is not suited for. What would I do? Hmm. Years ago, Mike Tilson, a guy who once won a UNIX-man-of-the-year award and because a VP of SCO when they took over HCR http://web.mit.edu/comm-forum/mit6/papers/Maxwell.pdf wrote an accelerator for the V7 file system that mapped the inodes into fast store after boot. For UNIX V7, which was very dependent on swap for roll-in-roll-out, this was a great boon. If I could find a way to do this with modern file systems it would help. Name resolution and inode activity have been improved with caching but are still and expensive part of file activity. What I would try would be to use union file system. I'll look to see if I could overlay /lib and possibly /usr/lib, and /bin and /usr/bin so that the most used files were copied to the SSD. Not on a per boot basis, but on some kind of cumulative basis. Yes, some provision would be needed for when the 'on disk' copy was updated. Why would I do this? The libraries are, except for updates, read only and so would not cause excess traffic to the SSD. They are mapped on demand. Being able to read them from the SSD would speed up applications whereas having /boot on the SSD would speed up ONLY booting. A serious view of things would carry out a traffic analysis to see what files were the best candidate for this kind of accelerator. No doubt it would differ between systems. -- Our institutions and values are in jeopardy as the mores of the market pervade all social life in this country. Loyalty, honesty, courage, discipline, patriotism, and commitment to family are being crowded out by the goals and rules of economic rationality -- do whatever makes the most money. --Barry Schwartz -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org