On Wed, 7 Apr 2010, Erik Trimble wrote:
One thing Richard or Bob might be able to answer better is the tradeoff between getting a cheap/small SSD for L2ARC and buying more RAM. That is, I don't have a good feel for whether (for your normal usage case), it would be better to get 8GB of more RAM, or buy something like a cheap 40-60GB SSD for use as an L2ARC (or some combinations of the two). SSDs in that size range are $150-200, which is what 8GB of DDR1 ECC RAM will likely cost.
If the storage is primarily used for single-user streamed video playback, data caching will have little value (data is accessed only once) and there may even be value to disabling data caching entirely (but cache metadata). The only useful data caching would be to support file prefetch. If data caching is disabled then the total RAM requirement may be reduced. If the storage will serve other purposes as well, then retaining the caching and buying more RAM is a wise idea.
Zfs has a design weakness in that any substantial writes during streaming playback may temporarily interrupt (hickup) the streaming playback. This weakness seems to be inherent to zfs although there are tuning options to reduce its effect.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
