The default install for OpenSolaris creates a single root pool, and creates a swap and dump dataset within this pool. In a mutipool environment, would be make sense to add swap to a pool outside or the root pool, either as the sole swap dataset to be used or as extra swap ? Would this have any performance implications ? cheers Matt
On 3/03/10 11:19 PM, Matt Keenan wrote:> The default install for OpenSolaris creates a single root pool, and > creates a swap and dump dataset within this pool. > > In a mutipool environment, would be make sense to add swap to a pool > outside or the root pool, either as the sole swap dataset to be used or > as extra swap ?Yes. This is what I do at home, and what we do on the onnv gate machines - we''ve got swap in rpool and a separate, dedicated, swap pool.> Would this have any performance implications ?Negative performance implications? none that I know of. James C. McPherson -- Senior Software Engineer, Solaris Sun Microsystems http://www.jmcp.homeunix.com/blog
>The default install for OpenSolaris creates a single root pool, and creates a >swap and dump dataset within this pool. > >In a mutipool environment, would be make sense to add swap to a pool outside or >the root pool, either as the sole swap dataset to be used or as extra swap ? > >Would this have any performance implications ?My own experience is that the zvol swap devices are much slower than swap directly to disk. Perhaps because I had compression on in the rpool, but any form of data copying/compressing or caching for swap is a no-no: you use more memory and you need to evict more pages. Casper
On 03/03/10 05:19, Matt Keenan wrote:> In a multipool environment, would be make sense to add swap to a pool outside or > the root pool, either as the sole swap dataset to be used or as extra swap ?Yes. I do it routinely, primarily to preserve space on boot disks on large-memory systems. swap can go in any pool, while dump has the same limitations as root: single top-level vdev, single-disk or mirrors only.> Would this have any performance implications ?If the non-root pool has many spindles, random read I/O should be faster and thus swap i/o should be faster. I haven''t attempted to measure if this makes a difference. I generally set primarycache=metadata on swap zvols but I also haven''t been able to measure whether it makes any difference. My users do complain when /tmp fills because there isn''t sufficient swap so I do know I need large amounts of swap on these systems. (when migrating one such system from Nevada to Opensolaris recently I forgot to add swap to /etc/vfstab). - Bill