EqualLogic PS3800XV Storage Array

Most of the attention given to rack mounted storage over the last year has been around the explosion in secondary storage - devices containing large capacity SATA drives. While some vendors have been happy to target these as primary storage, their large capacities and slower speeds are not well suited to high speed, transactional environments.

To address this market, EqualLogic has released the PS3800XV, the first in a range of Serial Attached SCSI (SAS) devices that are direct replacements for fibre channel SCSI arrays. The target market is those running databases, mail servers and even CAD systems.

The PS3800XV comes fully assembled. The chassis contains 16 x 15,000 rpm SAS drives each capable of holding 147GB and mounted in their own caddies. To power these drives there are two 450W hot plug power supplies.

Network and communications is handled through controller boards and the PS3800XV ships with two controllers, each of which has three gigabit Ethernet ports and a serial port.

There is a separate box containing accessories and inside here you will find serial and power cables. There is an anti-static band should you need to work inside the enclosure and rack mount kit with rails. Two documentation packs contain quick start kit, hardware guide and software.

What is missing is also of interest. EqualLogic see no need to ship a spare drive. This is because these are SAS and not SATA drives so they are less likely to fail. No network cables was a surprise.

Getting started was not quite as easy as expected. As the PS3800XV comes fully loaded it becomes a heavy box. In order to get it into the rack without risking any injury takes a little time.

Mounting the rails in the rack and onto the chassis was very easy. Before installing, however, we removed all of the drives. They slid out smoothly with no force needed. The drives have plenty of airflow around them so even though they are spinning at 15,000 rpm, any heat generated is easily dissipated.

We also removed the two PSUs to reduce the weight of the chassis and these slid out with no problems. Out of interest, we also removed the two controller cards which provided us with access to the Compact Flash cards that they use to store system settings.

Once this was done, the weight was very manageable and the chassis was quickly inserted into the rack.

Reinserting everything was quick and easy. Once all of this had been done, we connected the power leads attached the PS3800XV to the gigabit switch and fired up the array. Power-up took a little time as the drives seemed to spin up individually. This allowed up to see how much vibration there was as each drive was added and the unit was rock solid.

Connectivity to the network needs to be thought through. EqualLogic suggest two options. The first is to connect port zero on each controller card to the network switch. This is the minimum network configuration. For fault tolerance, you need to connect to multiple switches. Simply connecting all the ports to a single switch gains nothing.

Like all EqualLogic products, there is a quick way and a long way to initialise and configure an array. Previous EqualLogic products have required that the initial configuration was done through a DOS tool using a machine connected directly to the array. In a clear improvement, we were able to start with the GUI tool. The only time we went to the DOS tool was to completely reset the array before returning it to EqualLogic.

To get started, you insert the CD that comes with the array. It begins by preparing to install drivers by searching for any pre-installed components. One thing that it loads is the Microsoft iSCSI initiator. Strangely, even though the server used had been running an iSCSI array until just a few days before adding the PS3800XV, it still installed its own copy of the initiator.

The host integration program then installs the remote setup wizard, the auto-snapshot manager and finally the virtual disk service provider (VDSP). As a compliant Windows Server application, there is no need to reboot the server, even after adding the VDSP. The total space used to install these components is less than 5MB.

Once this is done you run the remote setup wizard which allows you to either locate new arrays or configure the machine to access a PS Series SAN. The wizard will find any arrays that have not been initialised and walk you through the initialisation. One of the options you get is to create a new storage group for this array or add the array into an existing storage group.

When creating a new group you need to setup accounts and passwords so that the Microsoft services can connect to the group. One of the things you will need to set is the RAID level for the arrays and here you have three choices, RAID 5, RAID 10 or RAID 50. You can change the RAID level later from RAID 10 or RAID 50 to RAID 5 or from RAID 10 to RAID 50.

Once set, the initialisation process is extremely fast, taking less than 10 minutes. After the array is initialised you can either launch the MS Storage Manager for SANs or connect to the array via a browser. The former is a Microsoft Management Console snap-in which is very easy to work with. The browser option is a Java utility. It can either be run as an applet in the browser or run as a standalone application.

After you are log in, the Group Manager window is displayed in summary mode. This displays a vast amount of information that takes some time to get to grips with. For anyone who has not worked with an EqualLogic array before, it is worth taking time to read through the help file and examine the various menus and reports.

Before creating volumes you need to complete the Group Configuration menu. One of the settings is to configure an NTP server entry for time synchronisation. If you are configuring multiple arrays for replication you should always use a time server to ensure accurate replication between the replicated partners.

Alerts and configuration data can be sent via email. However, there is a problem here. Most organisations require user accounts to login before sending email. EqualLogic does not provide a field for you to add the user password for this. As a result, you find yourself unable to send alerts via email. This is not an optional fix but something that EqualLogic needs to fix urgently. This does not affect information sent to a SYSLOG server however, so there is a solution for large organisations. Unfortunately a lot of medium sized organisations do not use a SYSLOG server and will need to find a workaround.

Under the Advanced options page, you configure snapshots and load balancing. Where the data is time sensitive and business critical, the snapshot option gives you the ability to protect against problems. Snapshots can be used as a halfway house for backup where the volume cannot be taken offline. Create a snapshot and then back that up. If the array is to be accessed by a large number of users, then you should consider using the load balancing feature.Only when you've finished the configuration should you start creating volumes. It might seem to make sense to create volumes first but if you want to use snapshots, for example, configuring the policy before attempting to create the volume ensures that you will only be able to create a volume whose snapshots can be properly supported.

The Create Volume utility is wizard driven and you set the size in either MB or GB. Once you have set the size of the volume and its parameters you will then have to wait for it to be created. This can take several hours depending on the size of the volume you are creating. This makes it preferably an overnight task.

At this point you are ready to start moving data onto your volumes.

Working with the Group Manager is actually quite fun once you've decided what you need to look at and where it is located.

Monitoring the behaviour and performance of a volume and array is essential. One of the key tools for any administrator is the log file. Every event is logged and you can configure the help file to always check the EqualLogic website for updated information.

When an event triggers an alarm, the Alarm panel, located at the bottom of the main Group Manager window will flash until you open the panel and examine the alarm. This quick visual indication of a problem is very helpful and better than relying on email and other notification methods.

The Group Monitoring menu allows you to see how a particular array group is behaving. From here you can see the configuration of all the components in a group, right down to each physical drive. This allows you to identify how each drive is doing and should you need to change a drive, you can see exactly where it is located.

The Performance Statistics monitor will give you detailed information on each drive, volume, storage pool and array. One of the problems of monitoring storage through the operating system is that storage arrays are presented as a single entity. This means that the monitoring tools cannot give you an accurate representation of what is happening with each drive or provide the necessary counters to identify problems below the volume level.

Not everyone uses Windows or wants to work through a GUI. For those who prefer to use the command line, EqualLogic provide a Command Line Interface (CLI) tool. This can be used under both Windows and Unix/Linux. With the next version of Windows Server (Longhorn) shipping with a non-GUI option, this means that EqualLogic does not have to rewrite their interface tools.

One of the advantages of a CLI is the ability to script common and frequent commands. Datacentres are becoming increasingly automated today so scripting is a big issue. To make life easier, EqualLogic has their own scripting language, EqualScript. It is based on the standard Perl scripting language and there are a number of modules and sample scripts provided by EqualLogic to get you started. For those working on Unix/Linux systems who probably use Perl already, this will enable them to automate management very quickly.

Earlier I mentioned the Compact Flash (CF) Card mounted on the Control Module. This holds the configuration information for the Control Module. Should a module fail, you can replace the module, put the old CF Card on the new module and be up and running immediately. No need to try and remember your previous configuration. This is a cool feature especially where arrays need to be kept running without downtime.

The ease of setup and management of the PS3800VX is outstanding and sets a benchmark for many of EqualLogic's competitors. Components are solid, move in and out easily and the cooling works very well indeed, something that is critical where 15,000 rpm drives are concerned.

The only downsides are the lack of a spare drive which every other storage vendor seems to supply, the lack of network cables and the problem with secure login for email. None of these are insurmountable and given the overall ease of use, it might seem churlish to highlight them. However, they are something that EqualLogic's competitors all do and it's hard to see how it would cause EqualLogic a problem.

There is no RAID 6 support but unlike arrays that use drives ranging from 500MB to 1TB, it is not required here.

At 28,300 this is not the cheapest 2.3TB you will every buy but don't forget that this is high speed, enterprise ready, SCSI replacement storage aimed at tier one applications. Other storage vendors are heavily focussed on the tier 2, high volume SATA market and this gives EqualLogic a clear advantage.

If you need mission critical storage to support transactional applications such as email and databases this is the solution for you.

Verdict

This is not the cheapest 2.3TB you will every buy but don't forget that this is high speed, enterprise ready, SCSI replacement storage aimed at tier one applications. However, if you need mission critical storage to support transactional applications such as email and databases this is the solution for you.

15,000 RPM, 146 GB SAS drives 16 drive chassis Dual controller modules, each with 64-bit dual core RISC processor Battery-backed and mirrored RAID cache Automatic RAID 5, RAID 10, and RAID 50 configuration Highly flexible, space-efficient volume snapshots Auto-capable volume replication Complete storage solution with heterogeneous OS support Automatic load balancing Scales without service disruption Fully interoperable with the entire PS Series product line 2.3 TB of raw capacity 60,000 IOPS and 300 MB/sec EqualLogic Multi-path I/O