On Mon, 3 Aug 2009, Joachim Sandvik wrote:
Will the IOPS in the mirrored setup be so good, that a ssd cache disk might not be needed? And i then might go for 10 x mirror with 2 x 1tb instead of 9? I really dont think that space will be an issue
This really depends on how many synchronous writes you have. NFS writes are mostly/all synchronous writes. Other protocols may require the same or fewer synchronous writes.
SSDs can be spectacular at improving NFS write performance.
How would memory inpact the performance? memory is quite cheap now a days, so going to 48gb will be quite inexpencive. or should i go for 24gb and use the rest of the money for faster ssd's?
This depends on the balance of reads vs writes, and how many synchronous writes you have to worry about. It also depends on the size of the working set. If the RAM is smaller than the working set, then IOPS will be wasted. Even though synchronous writes are the bottleneck for some uses, most servers do mostly reads. Nothing reads faster than RAM. A SSD read cache might return data at 200MB/s but RAM can return it at 3000MB/s or more. ZFS writes will also be faster with more RAM when existing data is updated since the 128K block to be updated does not need to be read again before being written.
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
