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Which external storgage unit goes with the rp3440 or rp4440 servers?

 
Philip Chan_1
Respected Contributor

Which external storgage unit goes with the rp3440 or rp4440 servers?

Hi,

I'm now considering to replace a L2000 440Mhz 3-way machine by either the rp3440 1G 4-way or rp4440 1G 4-way. This server will run Sybase on it and due to Sybase's architectural requirement, it would require at least 4 disks to serve redundancy purpose and separation of data and log activities to achieve best I/O performance. I understand that the maximum number of internal disks are just 3 and 2 for rp3440 and rp4440 respectively. Since these server models are so new, can someone suggest a good external storage unit that would go well with them? note that I intended to run MirrorUX on the disks to provide resilience.

Besides part numbers, a bit of explanation on each parts is much appreciated.

Thanks in advance for your advice.

Regards.
10 REPLIES 10
G. Vrijhoeven
Honored Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

HI Philip,

I think your storage solution does not directly depends on your server choice but on you SCSI controller choice. It might be possible to use the same disks/cabinets that were connected to the L2000. Do you migrate for I/O performance issues or CPU cap?

Gideon
Philip Chan_1
Respected Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

We are migrating due to CPU issue, that is pretty obvious as we saw during our investigation on the system for the past couple months. As for I/O, a minimum of 4 disks should serve our purpose well. To cater for future growth, I believe having 8 disks is the most (internal+external) for us. I tend to think that fibra-channel is not needed for this scale of I/O system.

Comments?
Leif Halvarsson_2
Honored Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

Hi,

To take real advance of the performance of the new rp34xx/rp44xx you should consider a RAID system with a rather large number of disks (> 10). One solution may be the RAID160 SA controller and a ds2405 JBOD disk system but as the servers is very new I can't find out if the RAID 160 SA is supported for rp34xx/rp44xx (you have to check with HP sales).
Philip Chan_1
Respected Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?



I think mirroring is faster than raid-5. I understand that there is a theory saying for reading/writing the same amount of data, having a larger number of disks working in parallel would be quicker than just having 1 or 2 to do the same I/O job, however I personally think that this is wrong because the overheads on co-ordinating many disks to work is fairly significant (also got to wait for the slowest disk to return data), therefore the speed gain would not be great, or even making the system slower than those non-raid'ed systems. On the other hand, mirroring is a more predictable approach for the purpose of redundancy, providing that cost is not a concern. We actually done disk tests on raid-1 (mirroring) against raid-5 and concluded with my expected result (raid-1 is faster). I could be wrong and am happy to learn that I'm wrong if someone would correct me on this (with explanation of course).

To go with the rp3440 server, I'm actually thinking about the ds2110 which can host 4 disk at most in one enclosure and we probably start with 2 disks in it (2 others from internal drive bases, making a total of 4 to fit our requirement). If more disks are required in the future, we would just do daisy-chain with the ds2110.

Comments are all welcome.

Regards,
Philip
Philip Chan_1
Respected Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

BTW, does anyone know the differences between ds2100 and ds2110? thanks.
Stefan Stechemesser
Honored Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

Hi Philip,

the DS2110 is ultra320 cabable, the DS2100 only ultra160.

I agree to your point of view that this would be the best solution for you. No additional I/O cards are needed (Core I/O has ultra160 SCSI) and if the disk performance is not your bottleneck, I would not recomend to use a raid160 card.

By the way, raid is normaly much faster than single disk access, because the disk itself is the slowest part in a SCSI subsystem. The bus is much faster than one disk => if you read simultanously from multiple disk, you can increase the performance. Raid 5 has the disadvantage that writing is a bit slower, because parity data has to be calculated. But the raid160 card is very fast in doing this (and no CPU recources are used by this).
I know several customers who use Raid Cards with RAID0 Luns, which has the highest performance (of cause the lowest redundance, LVM can also do RAID0, but mirroring + RAID0 is impossible with LVM only).

Another point is that the DS2xxx enclosures are NOT SUPPORTED with the Raid160 card, only the StorageWorks Enclosures 4314T, 4314R,4354R and MSA30.

Best regards

Stefan Stechemesser
Philip Chan_1
Respected Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?


I wonder which is the better way to provide resilience for disk access,

1. buy 2 ds2110 disk systems, hook up each to an independent U320 SCSI interface (2 in total), then run MirrorUX on them.

2. buy 1 ds2300, have two independent U320 SCSI interfaces connecting to its controllers, again run MirrorUX on the disks

Which way is more economical? which is the more sensible approach?

I'm not that familiar with HP disk systems, your comments are appreciated. Thanks.

Ted Buis
Honored Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

The DS2405 is FC not SCSI so it would require a FC adapter. I suggest contacting your HP sales contact for a quotation. That way you can get all the cables, services all specified that you need.
Mom 6
Philip Chan_1
Respected Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

I believe Ultra3-320 is sufficient for our I/O requirement that's why I thought of using ds2300 instead of ds2405 (of course I would go for this one if I have no budgetary concern). In fact, I have already asked our HP sales rep to provide quotations for both config for cost comparison. Besides, I would also like to hear comments from the real users out there. Like I said in previous messages, another option I could think of is having 2x ds3110 then form a resilient mechanism around them. Understand that this may not be an usual approach that's why I would like to hear comments from you guys.
Bill Hassell
Honored Contributor

Re: Which external storgage unit goes with the rp3440 or rp4440 servers?

RAID-5 compared with mirroring is not much of a performance consideration as long as the RAID tasks are handled by an array controller rather than the computer. A general purpose computer talking over a slow SCSI interface can't begin to perform as well as a specialized array controller with a large memory cache. RAID 5 accomplishes redundancy and hot replacement with the fewest number of disks.


Bill Hassell, sysadmin