.. also SSD won't necessary use Flash technology in the future, there are already alternatives close to production level, which solve exactly that write problem. In any case, in few years we will have such a hierarchical persistent memory from slow SSD up to fastest CPU caches available. S, Michael Haupt piše:
... BTW that's what I meant with optimisations.
Am 14.01.2012 um 19:34 schrieb Guido Stepken <gstepken@googlemail.com <mailto:gstepken@googlemail.com>>:
Read about "wear leveling"? So, no problem with write cycles. For example yffs2 filesystem gives you a tremendous gain in lifetime of your USB flash storage.
regards, Guido Stepken
Am 14.01.2012 15:56 schrieb "Michael Haupt" <mhaupt@gmail.com <mailto:mhaupt@gmail.com>>:
Hi,
2012/1/14 Janko Mivšek <janko.mivsek@eranova.si <mailto:janko.mivsek@eranova.si>>: > Conclusion? Why RAM won't be just a L3 cache in a whole hiearchy of > caching from SSD up to CPU? Automatic, supported by OS or even hardware, > as CPU caches are? Then image wont be needed to be read to RAM and > snapshoted back to disk, it can be run directly from disk.
SSDs are Flash memory. The number of write cycles is limited before the memory starts to fail. Smalltalk frequently performs GC, which involves moving objects, i.e., writing. Writing is also much slower than reading, and AFAIK possible only block-wise (with a block being significantly larger than your average object). Flash file systems apply optimisations to distribute writing evenly, avoiding excessive writing in some places and consequent earlier failure.
Best,
Michael
-- Janko Mivšek Svetovalec za informatiko Eranova d.o.o. Ljubljana, Slovenija www.eranova.si tel: 01 514 22 55 faks: 01 514 22 56 gsm: 031 674 565