Mike Gerdts wrote: > On Tue, Jul 1, 2008 at 5:56 AM, Darren J Moffat <[EMAIL PROTECTED]> wrote: >> Instead we should take it completely out of their hands and do it all >> dynamically when it is needed. Now that we can swap on a ZVOL and ZVOLs >> can be extended this is much easier to deal with and we don't lose the >> benefit of protected swap devices (in fact we have much more than we had >> with SVM). > > Are you suggesting that if I have a system that has 500 MB swap free > and someone starts up another JVM with a 16 GB heap that swap should > automatically grow by 16+ GB right at that time? I have seen times > where applications "require" X GB of RAM, make the reservation, then > never dirty more than X/2 GB of pages. In these cases dynamically > growing swap to a certain point may be OK.
Not at all, and I don't see how you could get that assumption from what I said. I said "dynamically when it is needed". > In most cases, however, I see this as a recipe for disaster. I would > rather have an application die (and likely restart via SMF) because it > can't get the memory that it requested than have heavy paging bring > the system to such a crawl that transactions time out and it takes > tens of minutes for administrators to log in and shut down some > workload. The app that can't start will likely do so during a > maintenance window. The app that causes the system to crawl will, > with all likelihood, do so during peak production or when the admin is > in bed. I would not favour a system where the admin had no control over swap. I'm just suggesting that in many cases where swap is actually needed there is no real need for the admin to be involved in managing the swap and its size should not need to be predetermined. -- Darren J Moffat _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
