topic Re: EVA 4400 Disk Question in Disk Enclosures

EVA 4400 Disk Question

rbanse — Thu, 20 Oct 2011 20:44:23 GMT

In a conundrum, we have 6 open slots on our EVA, so we decided to purchase 6 of the 1 TB FATA drives. Our current drives in the EVA are the FC 450 GB drives. I went to create a new disk group, and it says I need at least 8 disks to create a new disk group. I only have 6 disks, and the remaining slots are all used up in our 3 EVA shelves. What does a person do now? Can I somehow remove two of the FC 450 gb disks and then add two more of the 1 TB FATA disks? We are near full capacity with our current disk group, so by removing two disks, I would think that would have a big affect on things.

Thanks.

Re: EVA 4400 Disk Question

hvhari — Fri, 21 Oct 2011 12:21:53 GMT

I would prefer adding FC disks to the 6 slots and configure them into same disk group.

Removing the two disks from existing FC disks (by ungrouping them, if there is free space available in EVA) can result in the disk group getting more occupied which can affect performance of the array.

There is good explanation of disk groups, occupancy , preferred usage etc. in the HP Guided troubleshooting.

http://h20584.www2.hp.com/hpgt/guides/select?lang=en&cc=us&prodTypeId=12169&prodSeriesId=3664763&lang=en&cc=us.

Re: EVA 4400 Disk Question

rbanse — Fri, 21 Oct 2011 12:49:39 GMT

Unforn., adding more FC disks is not an option right now for us due to costs. We already have 30 FC disks in our array (450 gb ones), and adding 6 more would cost us $13,000 or so. We are looking at putting these cheaper FATA disks in due to much lower cost and not needing Tier 2 storage but Tier 3 for backups and other low-end data.

Re: EVA 4400 Disk Question

Steven Clementi — Fri, 21 Oct 2011 15:26:51 GMT

If you got a quote for 6 450GB drives for 13,000 dollars, I suggest you find yourself a new reseller.

Re: EVA 4400 Disk Question

rbanse — Fri, 21 Oct 2011 16:30:03 GMT

Sorry, $4500 for 6 FC 450 gb drives!

Re: EVA 4400 Disk Question

hvhari — Sat, 22 Oct 2011 13:03:40 GMT

If you "must" go for FATA disks please ensure

01. Have few of the existing LUNs removed to ensure that you have atleast 10-15% free space after removal/un-grouping of two disks. This plays an important role in having an acceptable performance on a heavily utilised array and during any disk replacements.

02. Create a new disk group for FATA drives and do take care of work load in this disk group. As these disks are NOT meant for 24x7 duty cycle.

Re: EVA 4400 Disk Question

rbanse — Sat, 22 Oct 2011 21:09:46 GMT

Thanks for all the responses. Currently we have 64 gb remaining in our EVA. Sounds like this is not ideal. Not a whole lot I can do about this right now though unless we purchase another shelf. So I found two LUN's that I will be able to remove, about 1.1 tb of space. After removing these two luns, I then should be able to unjoin two 400 gb FC disks and then create no more LUN's for this disk group, leaving around 400 gb free. Isn't there a spare disk though in the EVA in case of problems where another disk may go bad, and then this spare disk gets used until the other disk gets replaced? We do plan on purchasing two more FATA disks for a total of 8. Should I then be able to create my new FATA disk group? It's my understanding you need at least 8 disks to create a disk group. We are only planning on using the FATA disks for Tier 3 storage (user home drives, backups, etc), but it will be accessed 24/7. Hopefully we do not run into any issues. Ideally we should be purchasing another shelf, but due to money constraints, this is not a possibility right now.

Thanks again.