EXCLUSIVE: IBM System Storage DS3400 Express

Editor's Choice
Price
£3,474

IBM's storage division has been busy of late and now has a very sharp focus on the burgeoning small to medium business market. Its latest System Storage DS3400 directly targets this sector and aims to deliver an affordable and easily configured FC disk array with plenty of fault tolerance and expansion potential.

The DS3400 is a replacement for IBM's elderly TotalStorage DS400 and is based around the new Engenio 1932 Storage System which was unveiled by LSI Logic earlier this year. It brings in a number of new and welcome features as out goes SCSI to be replaced by SAS. The 2U chassis supports up to twelve hot-swap drives and can handle up to two controllers each equipped with two 4Gbps FC SFP ports and a Fast Ethernet management port. Expansion potential is looking good as the x4 SAS port on each controller is used to link up to three EXP3000 units allowing capacity to grow to over 14TB.

The Express models include either single or dual controllers along with all the necessary fibre cables and SFP modules. The review system included both controllers and prices for this start at 5,071. This doesn't include any hard disks but you can pick and choose from the full range of 15k SAS drives. Power redundancy comes as standard as all models include a pair of 515W hot-plug supplies and each controllers has 512MB of battery backed up cache which can be upgraded to 1GB for the princely sum of around 450.

The controllers can support an active/active mode where they carry out cache mirroring in this configuration. IBM also supports Microsoft's MPIO (multi-path I/O) which uses multiple hardware components to create redundant paths from hosts to storage volumes. Essentially, MPIO lets Windows see the same disk twice which allows paths from two controllers to the same logical drive to co-exist. If one controller fails the drive will be automatically reassigned to the other controller. A valuable feature here is that unlike much of the competition, IBM doesn't charge for its DSM (device specific module).

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A key selling point is ease of installation and we have no problems here as we had the system out of the box and running inside an hour. The array is managed with the bundled Storage Manager 2 Client utility (SMC2) which is a rebadged version of LSI's Engenio Simplicity Manager. It's certainly easy enough to use and runs a discovery routine that searches the network for storage arrays, displays them ready for configuration and presents wizards galore. Logical drive configuration comes first where you can leave SMC2 to automatically carve up available drives into a RAID-5 array with hot-standby or you can do it manually. The latter is easy enough as you pick your drives and decide on an array type. Note that the appliance doesn't support RAID-6 but you can choose from RAID0, 1, 3, 5 and 10 and designate drives as hot-spares.

Next, you create host to logical drive mappings and we encountered a minor problem here as the task wizard was unable to automatically find our two direct attached hosts systems. It was more of an irritation than a problem as we just had to manually declare them to the appliance where we provided meaningful names and associated these with the relevant host where both our test systems were, strangely enough, being displayed in this screen. You can decide whether hosts will share access to logical drive mappings in which case they can be placed in host groups. Called partitioning, the system comes preconfigured with support for four partitions but you can license up to sixteen. Alternatively, you can restrict access and allow one host only to use a logical drive.

The appliance supports dynamic capacity expansion where you can drop in more disks or expansion cabinets and add them on the fly to existing logical drives. We tested this by hot-plugging an extra disk into the array which was picked up smartly by SMC2 and made ready for use. Using the Add Free Capacity option you simply select an existing array and assign the new drive to it.

IBM offers some useful optional features with the FlashCopy snapshot at the top of the list which takes point in time copies of selected logical drives. VolumeCopy provides a cloning service where it creates a duplicate of one logical drive to another location within the same appliance - useful for testing. You can reduce the impact the cloning phase has on normal operations by assigning it one of five priorities.

For testing we used a pair of Supermicro dual 3GHz Xeon 5160 servers running Windows Server 2003 R2 and equipped with QLogic QLE2460 4Gbps HBAs. Initially, we direct attached both servers to one controller and gave them shared access to a six drive RAID-5 array. We configured the freely available Iometer with four workers, 64KB transfer requests and 100 per cent read operations and saw one server report an impressive 374MB/sec average throughput. Naturally, write operations will take their toll with Iometer reporting 154MB/sec for this test.

With two servers in the mix we saw a cumulative read throughput on the array of 670MB/sec and a write speed of 85MB/sec. Next, we configured two four-drive RAID-5 arrays, assigned one to each controller and moved one server over to the second controller. With each server now using its own array and dedicated controller we saw cumulative read speeds increase to 736MB/sec whilst write operations came back with a much improved 202MB/sec.

It's no surprise that IBM is at the top of pile in the storage market as the DS3400 brings together everything that's good about FC SANs and presents them in a package that won't break the bank - it certainly looks far better value than products such as EMC's CLARiiON AX150. Apart from a minor glitch with host auto-discovery we found it easy to deploy and with the right configuration is capable of delivering a performance that rivals more costly FC solutions.

Verdict

IBM delivers a compact high capacity FC disk array that's a cinch to configure and manage, offers good performance and plenty of redundancy and can grow easily with demand.

2U rack mount chassis 12 disk bays 2 x 515W redundant power supplies Supports 15k SAS 73/146/300GB hot-swap hard disks 2 x RAID controllers each with 667MHz Intel XScale 512GB 333MHz cache memory expandable to 1GB Battery backup pack Supports RAID0, 1, 3, 5, 10, hot-swap and hot-standby 2 x 4Gbps FC host ports SAS disk expansion port 10/100BaseTX Ethernet

Express Kit includes: 4 x 5m FC LC-LC Cables 4 x 4Gbps SW SFP transceivers IBM Storage Manager 2 Client software

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