> Since, best case, 4 gbit FC can transfer 4 GBytes of data in about 10 > seconds, you will fill it up, even with the backend writing out data as fast > as it can, in about 20 seconds. Once the nvram is full, you will only see > the backend (e.g. 2 Gbit) rate.
Asif, the above statement from Andrew is important to consider... keeping in mind that although the 1 controller that you currently use (remember, B is on standby in your original config) contains 2GB of memory/cache ... you don't actually have 2GB to play with. The 6140 is not a dumb device but runs code, which use memory ... someone from sun's hardware department (or LSI) can probably tell you the precise number ... but after bootup of the unit you should have less than 2GB of memory usable. I believe it to be close to 2GB ... not so with ALL hardware controller units ... some might only leave you with 1GB after bootup. Anyways ... to fill up that cache at full 4Gbit speed will only take ... 2GB / 400MB/s, ie 5 seconds... IF you can pump 400MB/s. Unless you actively map LUN's to controller B and use MPXio ... you are not using the cache on controller B. (not taking into account cache mirroring) My production configurations for a 6140 is 2 links to controller A (via 2 switches) and 2 to controller B (2 switches) for standby. Since it's switched fabric, it's also full duplex :) Quote from "Just the facts - 6140" : "the Sun StorageTek 6140 array can sustain 1500 MB/s on cache reads, which is 94 percent of the theoretical maximum throughput of its 4 Gb/s interfaces; the Sun StorageTek 6140 array can sustain 990 MB/s on disk reads with 4 Gb/s disk drives and interfaces. And by delivering 850 MB/s on sustained writes to disk, the Sun StorageTek 6140 array can sufficiently handle write-intensive applications as well." Also ... "Cache mirroring protects unwritten data during a controller or cache memory failure. When cache mirroring is enabled, the data that writes to the cache memory of one controller also writes to the cache memory of the other controller. Therefore, if one controller fails, the other can complete all outstanding write operations. This cache parameter is set on a per volume basis." Which means that if you have it switched on AND use both of your controllers actively for I/O, you will still only have 1 controller's memory available (since number 2 will be a mirror). _______________________________________________ storage-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/storage-discuss
