Nexsan has always focused tightly on large businesses looking for heaps of network storage but without the benefit of a blank chequebook.
We’ve always been hugely impressed with its SATABeast appliance as it offers a monster capacity combined with top value and performance. The SATABoy also received a warm welcome here at [i]IT PRO[/i] with its combination of capacity and value earning it a coveted Editor’s Choice award.
With its latest SASBoy, Nexsan shifts its focus towards those businesses giving performance a higher priority over capacity. It’s aimed at applications such storage of X-ray or MRI images where content may be stored for long periods of time but users need fast access for searches.
The SASBoy is also being touted by Nexsan as the world’s first green SAS disk array. As it uses the same hardware as the SATABoy it gets the benefit of Nexsan’s AutoMAID (automatic massive array of idle disks) technology.
AutoMAID allows administrators to set time schedules for parking disk heads, reducing spin speeds and spinning them down. A problem with most disk arrays is their unhealthy appetite for power and AutoMAID is designed to reduce this significantly by turning drives off during extended periods of inactivity. This also cuts cooling demands and when drives are powered back up they do so sequentially to avoid any power surges.
The SASBoy on review came kitted out with a pair of hot-swap RAID controllers each equipped with 2GB of cache memory plus battery backup packs and providing support for RAID0, 1, 10, 4, 5 or 6 arrays. IP and FC SANs are on the menu as each controller has a pair of 4Gbps FC ports and two Gigabit iSCSI data ports. Fault tolerance is a key feature as well as the system can be configured such that no component represents a single point of failure.
With dual controllers you have four system modes available where you can use each controller as individual elements with no redundancy, set them so that volumes can be mapped to all four ports or combine them together as active/active partners with either two or four data ports presented. Note the two-port active/active mode does not require redundant paths on your host systems.
Nexsan’s CLI interface offers a well designed GUI rather than a command line whilst Nexsan’s new Storage Manager utility functions as an MMC snap-in so you can access the appliance directly from the Computer Management screen. The new web interface looks good and its quick start option automatically configures one RAID-5 array per controller. However, it’s easy enough to select your own RAID configuration and split them up into logical volumes.
Simple volumes are not supported but you can choose from any supported RAID array, dedicate hot-standby drives to specific arrays or designate them as floating spares. Volumes are created next and, depending on which system mode selected, you can decide which FC and data ports you want to map them to. Strong access controls are provided where you can limit host access to specific ports and decide whether they can have read only or read/write access.
[pb/]For our host systems we used Boston Supermicro dual Xeon 5100 and Dell PowerEdge 1950 dual Xeon 5300 servers both running Windows Server 2003 R2. Each was fitted with LSI 4Gbps FC HBAs and ran the latest Microsoft iSCSI initiator. Once FC connections were established we could see each host’s WWPN in the SASBoy’s web interface and could then dish out read/write access for them. The same applied to iSCSI as once the initiator had been logged in to the relevant target port its IQN was also displayed.
Performance over FC is impressive with the Iometer utility reporting a healthy raw read rate for one server of 366MB/sec – pretty much wirespeed for 4Gbps FC connections. With the second server also running Iometer on its own volume we saw a high cumulative read throughput of 731MB/sec. To get the best IP SAN performance we found you absolutely must use Gigabit jumbo frames. Without this configured we saw our two hosts return read speeds of only 54MB/sec apiece. Using a Netgear GSM7328S switch, we configured support for an MTU of 9216 bytes and activated support on our two servers. With jumbo frames rampaging across the network we saw each host now delivering between 94-97MB/sec raw read rates.
The SASBoy supports iSCSI’s MPIO feature and any host that uses Microsoft’s iSCSI initiator v2 and above will have the necessary DSM (device specific module) as standard. This lets you create redundant paths to storage volumes by allowing Windows to see the same disk twice so paths from two network controllers to the same logical drive can co-exist. For the SASBoy, we mapped one volume to both data ports on one controller and placed them in different subnets. We created a failover link using both network ports on our Dell server and with Iometer fired up we were able to disconnect one network cable and watch it continue unabated.
The AutoMAID feature worked very well during testing and we set the head parking time at two minutes and spin down at fifteen minutes. We were unable to select the second option for reducing spin speed as the Hitachi disks don’t support this feature. Nevertheless, after the first option came into force we saw consumption drop from 397W to 365W and after spin down this fell further to only 224W. When accessing the array from one our test hosts we could see no appreciable lag when the drives powered up ready for action.
To create the SASBoy, Nexsan has simply taken a SATABoy 2 system and replaced its drives with SAS models. These certainly made their presence felt in our performance tests and we found the AutoMAID feature can make big power savings whilst performance across the board is good.
Author: Dave Mitchell
Nexsan SASBoy