On Tue, 2006-04-11 at 10:55 +0200, Jure Pečar wrote: > On Mon, 10 Apr 2006 17:25:25 -0400 > Ming Zhang <mingz@xxxxxxxxxxx> wrote: > > > still, what is the main benefit of this cache? what u mean "local disk > > page cache"? use "local disk" as page cache or page cache for "local > > disk" or something else? > > I recently did some tests with ext3 data journaling and discovered that > large journals eat almost as much system memory as its size, which is a > bit crazy. Some might argue that configuring 4gb journal is crazy too, > but there are scenarios where this might be beneficial (think large > mail servers with gazillion small writes, which journal turns into one > big sequential write). So if something like external journal can be > implemented in dm, fs-agnostic and not as memory hungry, I'd be very > interested. even u journal is a big sequential write, u data write are not. so the combined performance will not have big difference. u mean u journal contain everything? including log and data? you might want to ask ext3 list and ask them why take so many memory with a 4GB journal. Also i think journal will write to disk very fast, so after written to disk, the ram can be reclaimed. also i do not see how a DM disk cache can help you on this. ming -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
