[opensuse] installation partition question
Friends -- 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. Suggestions appreciated. -- Fr David Ousley davidousley@verizon.net -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Tue, Feb 22, 2011 at 5:20 PM, Fr David Ousley <davidousley@verizon.net> wrote:
Friends --
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),
I would not put the SSD on swap for "speed". If you are using swap enough that speed matters, you will wear out your SSD long before you would otherwise. ie. Low-end SSD is designed for about 5,000 write cycles per Erase Block (EB). High-end for about 100,000 I think. Wear leveling allows you to spread that load around to unused EBs, but it will still be a problem. If you are hitting swap so much you care about speed, then SSD is a poor solution. If you're hitting it hard, either leave it on rotating disk or get more ram. If you only use swap now and then, but get frustrated that your whole machine slows down, then maybe. The trouble is you could start using swap more and more frequently and not realize it. Thus you wear out that expensive SSD for little real value. Greg -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Tue, 2011-02-22 at 18:47 -0500, Greg Freemyer wrote:
On Tue, Feb 22, 2011 at 5:20 PM, Fr David Ousley <davidousley@verizon.net> wrote:
Friends --
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),
I would not put the SSD on swap for "speed".
If you are using swap enough that speed matters, you will wear out your SSD long before you would otherwise.
ie. Low-end SSD is designed for about 5,000 write cycles per Erase Block (EB). High-end for about 100,000 I think. Wear leveling allows you to spread that load around to unused EBs, but it will still be a problem.
If you are hitting swap so much you care about speed, then SSD is a poor solution.
If you're hitting it hard, either leave it on rotating disk or get more ram.
If you only use swap now and then, but get frustrated that your whole machine slows down, then maybe. The trouble is you could start using swap more and more frequently and not realize it. Thus you wear out that expensive SSD for little real value.
Absolutely true, In the bad-old-days, swap was a mere fact-of-life. But with the price of mem dropping continously things have changed. In general, swap should be treated as the safety lane on the high way: "It is there, but should never use it unless emergencies arises" Otherwise, there is something wrong in the system.... So if you _add_ a SSD only for speeding up things, very well, put all the things there that hardly changes: /boot, /usr, /lib, perhaps mount them read-only. And keep stuff that changes continuously (/var, /srv, /tmp) on traditional disks. Other story is however if you _only_ have sdd, for instance for noise, power consumption. Some partitions (/tmp, /var/run) can entirely be placed in mem, using tmpfs, thus increasing the claim on mem. Leaves us with swap in that condition: If you don't define swap (possible) and a process gets greedy, the much feered Out-Of-Mem steps in and might kill processes you rather would like the live. On the other hand, as clearly stated above, swap on SDD will have a bad impact on the life expectency of your SDD. hw -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Thanks to one and all -- very helpful in getting the system set up. -- Fr David Ousley davidousley@verizon.net
If you only use swap now and then, but get frustrated that your whole machine slows down, then maybe. The trouble is you could start using swap more and more frequently and not realize it. Thus you wear out that expensive SSD for little real value.
Absolutely true,
In the bad-old-days, swap was a mere fact-of-life. But with the price of mem dropping continously things have changed. In general, swap should be treated as the safety lane on the high way: "It is there, but should never use it unless emergencies arises" Otherwise, there is something wrong in the system....
So if you _add_ a SSD only for speeding up things, very well, put all the things there that hardly changes: /boot, /usr, /lib, perhaps mount them read-only. And keep stuff that changes continuously (/var, /srv, /tmp) on traditional disks.
Other story is however if you _only_ have sdd, for instance for noise, power consumption. Some partitions (/tmp, /var/run) can entirely be placed in mem, using tmpfs, thus increasing the claim on mem. Leaves us with swap in that condition: If you don't define swap (possible) and a process gets greedy, the much feered Out-Of-Mem steps in and might kill processes you rather would like the live. On the other hand, as clearly stated above, swap on SDD will have a bad impact on the life expectency of your SDD.
hw -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
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
participants (4)
-
Anton Aylward -
Fr David Ousley -
Greg Freemyer -
Hans Witvliet