Dell EqualLogic PS6000XV SAN Storage Appliance Inverness
Dell EqualLogic PS6000XV SAN Storage Appliance
Acquiring IP SAN specialists EqualLogic early last year gave Dell a solid range of enterprise solutions that has enabled it to compete on an equal footing with the established names in the network storage market. It hasn’t sat still either and in this exclusive review we look at the new EqualLogic PS6000XV, which offers an extensive range of features and more than a few new ones as well.
The price includes a bumper bundle of extras including snapshots, thin provisioning and replication – features certain other vendors consider optional and charge an arm and a leg for. The PS6000XV comes as standard with a pair of controllers for full fault tolerance and these have been redesigned with four Gigabit data ports and support for RAID6.
The controllers function in active/standby mode and all operations are synchronised across both controllers. The four network ports in the primary controller are all assigned their own IP address but are grouped together under a virtual IP address where the appliance carries out load balancing.
You can grow with demand as physical appliances are gathered together in groups and presented as logical storage pools. Each appliance manages its own RAID array but storage of all group members is made available as a single entity. Virtual volumes are created within this space and presented as iSCSI targets but the volume data is spread across all appliances and drives in the group. Expanding capacity on the fly is possible as you simply add new appliances to the group as required.
We had no problems deploying the PS6000XV in the lab as Dell’s new Windows Remote Setup Wizard searches for new arrays and provides a quick install routine. You choose a member name and assign it an IP address, pick your RAID array and decide whether to join an existing group or create a new one.
The Group Manager console is very intuitive and provides easy access to functions such as group, storage pool and volume creation. For the latter you choose a storage pool, decide on a volume size and add access restrictions, where you can limit host access by CHAP authentication, IP address or initiator name.
Thin provisioning can be configured during volume creation and you decide how much physical space to start with. The appliance uses three watermarks where the minimum size is 10 per cent of the virtual volume. When the volume is 95 per cent full the system starts throttling back I/O performance to enable administrators time to increase the volume size. Once you reach the critical watermark the volume is placed offline.
Snapshots are set up during volume creation where you decide how much space should be set aside for them and at any time you can promote snapshots as new volumes. A thin provisioned volume will have its snapshots and replicas thinly provisioned and you can also swap on the fly between classic and thin provisioned volumes as well.
For replication, snapshots of selected volumes are stored in other groups called replication partners. During setup you can choose one-way replication to another group, bi-directional replication between groups or designate one group as a central location to which multiple groups can be replicated. If a volume gets lost or damaged you just clone a copy of the replicated volume and promote it as a new volume.
Dell’s new SAN HeadQuarters is designed to manage multiple appliances from a central console. You add your groups, which all appear in the left pane along with a choice selection of statistics and graphs for each one. You can view detailed reports on capacity, which show the total space for the group and how it’s split up into volumes and snapshots.
A screen of combined graphs keeps you posted on network utilisation along with the number of logged in hosts and a separate screen provides a rundown on I/Os and average latency. We did notice that the table for disk performance didn’t work as most of the drives showed a zero throughput. The network option has a speedo dial showing overall utilisation of the virtual network port plus a summary for the group.
For testing we used four Dell PowerEdge R410 rack servers and connected them to the PS6000XV via a Force10 S25 Gigabit switch. We used all four ports on the primary controller and created a fourteen drive RAID-10 member array. Within this we created four 50GB partitions and limited target access to our test servers by their IP addresses.
Starting with one server we logged on to the first virtual volume and ran Iometer configured with four disk workers and 64KB sequential read transfer requests, where it reported a steady raw read throughput of 118MB/sec. With another server connected to the second volume we saw a cumulative throughput of 236MB/sec. Logging the third and fourth servers onto dedicated volumes saw this increase to 340MB/sec.
We tested further using two servers with MPIO links configured. Setting these up using Dell’s host integration tools is a cinch as you just connect two physical network ports, log on to the portal and target and Dell does the rest – no more mucking about manually configuring individual MPIO links.
One server reported an impressive 235MB/sec and with two in the mix we saw this increase to a whopping 470MB/sec cumulate read throughput – actually 30MB/sec higher than Dell’s claims. There are some prerequisites as you must have jumbo frames configured throughout along with flow control and all iSCSI initiators must have the least queue depth load balancing option selected.
The new PS6000 family of IP SAN appliances clearly deliver on Dell’s performance promises but offer a lot more besides. Support for virtualised environments is a high priority and the fact that snapshots, thin provisioning and replication are included makes this a great value appliance.
Author: Dave Mitchell