Disk System 2300, VA7410 and SAN

[kenny chia]

I am considering an Itanium system and there are 2 possible disk array system for Itanium(based on my experience in HP Enterprise Configurator web site).

Questions...
1. Is the VA7410 much faster than the DS2300? Assuming that one server is connected to one disk array

2. What are the benefits of SAN over the usual one disk array to one server configuration? Will there be an increase in speed and reliability?

[Leif Halvarsson_2]

Hi,
About SAN.
The only benefit with SAN in a point to point configuration is distance. There is no benefit in speed (as speed mainly depends on the number of drives in the disk system).

The VA and DS disk system is very different and (as I think) not comparable. DS2300 is a JBOD with a max. of 14 disks, VA7410 an adwanced RAID system which can hold more then 100 disks. Of course VA7410 is faster, more realiable etc. but also MUCH more expensive.

Theoretical you can get very high performance with a JBOD system if you can balance the load equal across all disks but for practical use you should also consider some kind of RAID controller together with the JBOD.

[Ron Lawson_1]

Another possible choice -- the MSA30 SB/DB storage system is supported with SmartArray RAID cards on most Itanium server/OS combinations.

[Ted Buis]

1. It depends. The ds2300 is only JBOD, not an array. If you will only connect the one system to the VA7410, then the default SCSI queue depth in HP-UX is 8 (256 max), and the VA7410 is 240, so you may want to do some tuning. The VA7410 has two redundancy groups, so you need a certain number of disks to get advantages of the virtual array stiping automatically for you. Can your application use the write cache to any advantage that is in the array? With any JBOD, you would likely be using MirrorDisk/UX, and have to do manual striping for best performance. Also, the default in HP-UX is to turn off the immediate report mode of the RAM on the disks themselves. Enabling immediate report mode adds additional risk of data loss in the event of power loss to the disk enclosure, but can improve performace (I have seen up to 4X). SmartArray Controllers have the advantage of a write cache, but generally are not as fast as the VA7410 could be, as they support smaller number of drives and smaller cache.

2.) The SAN's claim to fame is not speed but efficient utilization of storage among multiple systems. Disk arrays have high availabiltiy, but they have to be managed properly as intelligent devices. For example, the VA7410 should be properly shutdown, before one simple pulls the plug.
It does have an intelligent power switch to do that however.