Introduction

The Sun StorEdge Multipack is basically an external SCSI cabinet, but on steroids. It doesn't offer any inherent RAID capability as you must use Sun DiskSuite (in software) to do so. But as far as external SCSI cabinets go, this is one solid unit and comes in a six-drive and twelve-drive model, for both Wide SCSI and Fiber Channel.

Configuration and Performance

The configuration tested is a six-drive Wide SCSI unit with six 18GB, 7,200rpm drives. It's connected to a Sun Ultra 60 workstation with dual 450MHz/4MB UltraSPARC-II CPUs and 1GB of RAM. The drives are set up in a RAID 0+1 configuration using Sun (Solstice) DiskSuite v4.2 thusly (as reported by /usr/opt/SUNWmd/sbin/metastat):

d2: Mirror
    Submirror 0: d1
      State: Okay         
    Submirror 1: d0
      State: Okay         
    Pass: 1
    Read option: roundrobin (default)
    Write option: parallel (default)
    Size: 105100800 blocks

d1: Submirror of d2
    State: Okay         
    Size: 105100800 blocks
    Stripe 0: (interlace: 32 blocks)
	Device              Start Block  Dbase State        Hot Spare
	c1t9d0s6                   0     No    Okay         
	c1t10d0s6                  0     No    Okay         
	c1t11d0s6                  0     No    Okay         


d0: Submirror of d2
    State: Okay         
    Size: 105100800 blocks
    Stripe 0: (interlace: 32 blocks)
	Device              Start Block  Dbase State        Hot Spare
	c1t12d0s6                  0     No    Okay         
	c1t13d0s6                  0     No    Okay         
	c1t14d0s6                  0     No    Okay         

Something to watch for in the output above is the result of the "State:" fields. They should be reading "Okay" if your drives and RAID set up are in good health. The "Read" and "Write" options can also be tweaked for different performance characteristics. What the output basically says is that you have three drives that are striped on each side, and the first stripe-set is mirrored onto the second strip-set - or a RAID 0+1 configuration. Very fast, redundant but sadly very expensive. Out of the 108MB in drives, only 49GB is available once the drives are all formatted, partitioned and mounted up.

Here is a sample of a bonnie benchmark test I obtained from the Multipack. I ran the test twice, therefore you'll see two sets of output:

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
Multipack 100 10980 68.8 12438 18.2  6798 12.5  8403 92.2 52817 39.7 771.1 11.8

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
Multipack 100 10996 67.1 12557 17.7  7001 12.7 18336 87.7 68906 53.8 1040.5 16.9

Using scsiinfo (64-bit v4.6) a quick check that the drives contained within the Multipack are working and connected at peak efficiency ("40MB/s" and "clean" being good indicators). Here are the relevant portions of the output:

glm1: sd9,0 tgt 9 lun 0:
	Synchronous(40.000MB/sec) Clean TaggedQueuing Wide
glm1: sda,0 tgt 10 lun 0:
	Synchronous(40.000MB/sec) Clean TaggedQueuing Wide
glm1: sdb,0 tgt 11 lun 0:
	Synchronous(40.000MB/sec) Clean TaggedQueuing Wide
glm1: sdc,0 tgt 12 lun 0:
	Synchronous(40.000MB/sec) Clean TaggedQueuing Wide
glm1: sdd,0 tgt 13 lun 0:
	Synchronous(40.000MB/sec) Clean TaggedQueuing Wide
glm1: sde,0 tgt 14 lun 0:
	Synchronous(40.000MB/sec) Clean TaggedQueuing Wide

You could improve upon the performance of this set up by using 10,000rpm drives instead of the tested 7,200rpm drives - which would give you a faster response from the RAID. Good for databases and things that require faster random access. Save your money if you're reading mostly static files in a sequential fashion most of the time.

With an additional SCSI controller and Multipack with perhaps three of the drives from the first one, you can gain some more performance and redundancy over this configuration. Having an additional controller removes the single point of failure by having only a single controller, but also spreads the load across two SCSI channels rather than one. The side benefit of this is that you gain six more drive slots and basically doubled your potential throughput - but at double the price. At this point you may want to consider a hardware RAID solution, but this also incurs a large leap in total cost.

First Impressions

For one thing, it matches Sun hardware with the classic putty/purple trim and is about as large as two stacked shoeboxes. The front is an open grille to allow air to enter, where it is forced out via two 4" muffin fans in the back. Two Wide SCSI connections, both an in and an out are provided, in addition to the standard power cable port and adjacent power switch. In front is a sixpack of LEDs to indicate drive power and activity. You can switch the SCSI ID range from 1-6 to 9-14 and type of termination, which is built-in and automatic.

The unit is constructed extremely well - arguably in Sun's typical "over-engineered" way. The unit has a good heft to it and doesn't feel cheap. The two 4" muffin fans in the back of the unit are massive and draw a lot of air, but are a little on the loud side.

Drives are inserted into the Multipack via typical Sun drive sleds and support hot-swapping - holding up to six in total. There is also a twelve-drive unit available should you need more capacity. Both units can be chained together, up to two - to really max out capacity.

Benefits and Features

The biggest benefit of the Multipack is being able to connect up to six SCSI drives together in any number of configurations. You can use each drive as a separate volume, or use the Multipack in conjunction with Sun DiskSuite (part of Solaris) to set up a software RAID. With DiskSuite, you can quite readily set up a mirror (RAID 0) striping (RAID 1) or a combination of the two as a RAID 0+1, but this take a little bit of work. A quick RAID 5 setting is available also.

While Sun recommends that you use their drives, which are available in 9GB, 18GB and 36GB capacities, they are often rather expensive - two to three times the cost of comparable aftermarket drives. Of course, they include the necessary drive sled, which would be an additional cost on top of aftermarket drives, but with the savings you gain, you still come out ahead. For the ultimate in reliability and accountability, especially with warranties or Sun service contracts you might not have a choice than to get Sun drives. Either way, both solutions work.

Performance is very good and rated at 40MB/s. However, depending on how you configure the drives, you can affect performance to a great degree. Remember that the Multipack is a "dumb device" in that it merely provides you with a place to stash your drives. There is no inherent RAID hardware other than the hot-swap backplane, which means you'll need software to do your RAID. This will affect performance a bit over a hardware RAID solution, but you'll still be very happy with the cost/performance ratio obtained with the Multipack.

Being that the backplane is hot-swap compatible, as are most all Sun drives with the drive sled mounting system - in the event of a drive failure or upgrade, you don't have to shut down your system. This saves time and in the case of a mission-critical system, means you don't have to have any downtime. Many third-party SCSI cabinets are not hot-swap capable and merely mount drives rigidly in place. This means not only downing the server, but turning off the power - and breaking out the trusty screwdriver for a half hour or more of disassembly and reassembly work. A classic example of more money equating to more luxury and features. Well worth it, depending on your needs.

Downsides

Not so much a downside, but one thing you need to do from time to time as with any fan-cooled device, is to occasionally blow out the fans and front grille with compressed air to keep cooling efficient.

One downside is the need for Sun's drive sleds in order to mount drives in the Multipack. If you buy disk drives from Sun, then it's not much of an issue as they all come with the necessary sled. However, if you buy third party drives like I do - you'll need to procure some of these sleds elsewhere. I'm not sure what they cost new offhand, but on the used market, they average $25-35 apiece and with six drives, you're talking about $200US in mounting hardware alone. In the long run it is worth it to have a sled-based system, as this facilitates the hot-swap capability of the Multipack. While this makes it expensive for a home-use piece of hardware, for the data center it's just wonderful.

A minor annoyance is the fact that the keylock is located on the side panel, rather than in the front or back of the unit. This means that you can't leave a key in place if you have tight quarters. You shouldn't leave a key in place anyway - just lock or unlock it and take it out and put it someplace safe. It does work though - locking the side panel that you must remove in order to access the drives.

Long-Term Review

I've been using the Multipacks for a few years now, and there's not much to say other than that they are solid, reliable and almost maintanance free devices. Aside from occasional cleaning of the air passages and fans, unless a drive fails - you'll never need to touch the Multipack again.

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