Those of you fortunate enough to have worked with me in a professional capacity will know that I’m highly opinionated. I generally try not to be opinionated on this blog, preferring instead to provide guidance on tangible technical things. On this occasion, however, I’d like to offer my opinion. I overheard someone in the office recently saying that best practices are just best practices, you don’t have to follow them. Generally speaking, they’re right. You don’t have to do what the vendor tells you, particularly if it doesn’t suit your environment, circumstances, whatever. What annoys me, though, is the idea that’s been adopted by a few in my industry that they can just ignore documents that cover best practices because there’s no way the vendor would know what’s appropriate for their environment. At this point I call BS. These types of documents are put out there because the vendor wants you to use their product in the way it was meant to be used. And – get this – they want you to get value from using their product. The idea being that you’ll be happy with the product, and buy from the vendor again.
BP Guides aren’t just for overpaid consultants to wave at know-nothing customers. They’re actually really useful guidelines around which you can base your designs. Crazy notion, right?
So, to my point. EMC recommend, when you’re using FAST VP on the CLARiiON / VNX, to leave 10% free space in your tiers. The reason they recommend this is that they want FAST VP to have sufficient space to move slices between tiers. Otherwise you’ll get errors like this “712d841a Could not complete operation Relocate 0xB00031ED4 allocate slice failed because 0xe12d8709”. And you’ll get lots of them. Which means that FAST is unable to move slices around the pool. In which case why did you by FAST in the first place? For more information on these errors, check out emc274840 and emc286486 on Powerlink.
If you want an easy way to query a pool’s capacity, use the following naviseccli command:
naviseccli -h ipaddress storagepool -list -tiers
Pool Name: SP_DATA_1
Pool ID: 3
Tier Name: FC
Raid Type: r_5
User Capacity (GBs): 33812.06
Consumed Capacity (GBs): 15861.97
Available Capacity (GBs): 17950.10
Percent Subscribed: 46.91%
Data Targeted for Higher Tier (GBs): 0.00
Data Targeted for Lower Tier (GBs): 0.00
Disks (Type):
Bus 6 Enclosure 7 Disk 14 (Fibre Channel)
Bus 6 Enclosure 7 Disk 12 (Fibre Channel)
Bus 6 Enclosure 7 Disk 10 (Fibre Channel)
Bus 3 Enclosure 5 Disk 3 (Fibre Channel)
Bus 3 Enclosure 5 Disk 1 (Fibre Channel)
Bus 4 Enclosure 5 Disk 2 (Fibre Channel)
Bus 4 Enclosure 5 Disk 0 (Fibre Channel)
[snip]
Bus 2 Enclosure 6 Disk 14 (Fibre Channel)
Bus 2 Enclosure 6 Disk 12 (Fibre Channel)
Bus 2 Enclosure 6 Disk 10 (Fibre Channel)
Bus 0 Enclosure 2 Disk 0 (Fibre Channel)
Bus 5 Enclosure 6 Disk 8 (Fibre Channel)
Bus 3 Enclosure 2 Disk 4 (Fibre Channel)
Bus 7 Enclosure 5 Disk 6 (Fibre Channel)
Pool Name: SP_TEST_10
Pool ID: 2
Tier Name: FC
Raid Type: r_10
User Capacity (GBs): 1600.10
Consumed Capacity (GBs): 312.02
Available Capacity (GBs): 1288.08
Percent Subscribed: 19.50%
Data Targeted for Higher Tier (GBs): 0.00
Data Targeted for Lower Tier (GBs): 0.00
Disks (Type):
Bus 1 Enclosure 7 Disk 3 (Fibre Channel)
Bus 1 Enclosure 7 Disk 5 (Fibre Channel)
Bus 1 Enclosure 7 Disk 7 (Fibre Channel)
Bus 1 Enclosure 7 Disk 2 (Fibre Channel)
Bus 1 Enclosure 7 Disk 4 (Fibre Channel)
Bus 1 Enclosure 7 Disk 6 (Fibre Channel)
Bus 1 Enclosure 7 Disk 9 (Fibre Channel)
Bus 1 Enclosure 7 Disk 8 (Fibre Channel)
And if you want to get the status of FAST VP operations on your pools, use the following command:
naviseccli -h ipaddress autotiering -info -opstatus
Storage Pool Name: SP_DATA_1
Storage Pool ID: 3
Relocation Start Time: N/A
Relocation Stop Time: N/A
Relocation Status: Inactive
Relocation Type: N/A
Relocation Rate: N/A
Data to Move Up (GBs): 0.00
Data to Move Down (GBs): 0.00
Data Movement Completed (GBs): N/A
Estimated Time to Complete: N/A
Schedule Duration Remaining: N/A
Storage Pool Name: SP_TEST_10
Storage Pool ID: 2
Relocation Start Time: N/A
Relocation Stop Time: N/A
Relocation Status: Inactive
Relocation Type: N/A
Relocation Rate: N/A
Data to Move Up (GBs): 0.00
Data to Move Down (GBs): 0.00
Data Movement Completed (GBs): N/A
Estimated Time to Complete: N/A
Schedule Duration Remaining: N/A
And next time you’re looking at a pool with tiers that are full, think about what you can do to alleviate the issue, and think about why you’ve automatically ignored the best practices guide.
