[gpfsug-discuss] RAID config for SSD's used for data

[Luis Bolinches]

Hi

I'll give my opinion. Worth what you pay for. 

Do as many as you can, six in this case for the good reason you mentioned. 

But play with the callbacks so the migration happens on watermarks when it happens. Otherwise you might hit no space till your next policy run. 

The second is well documented on the redbook AFAIK

Cheers

--
Cheers

> On 19 Apr 2017, at 22.54, Buterbaugh, Kevin L <Kevin.Buterbaugh at Vanderbilt.Edu> wrote:
> 
> Hi All,
> 
> We currently have what I believe is a fairly typical setup … metadata for our GPFS filesystems is the only thing in the system pool and it’s on SSD, while data is on spinning disk (RAID 6 LUNs).  Everything connected via 8 Gb FC SAN.  8 NSD servers.  Roughly 1 PB usable space.
> 
> Now lets just say that you have a little bit of money to spend.  Your I/O demands aren’t great - in fact, they’re way on the low end … typical (cumulative) usage is 200 - 600 MB/sec read, less than that for writes.  But while GPFS has always been great and therefore you don’t need to Make GPFS Great Again, you do want to provide your users with the best possible environment.
> 
> So you’re considering the purchase of a dual-controller FC storage array with 12 or so 1.8 TB SSD’s in it, with the idea being that that storage would be in its’ own storage pool and that pool would be the default location for I/O for your main filesystem … at least for smaller files.  You intend to use mmapplypolicy nightly to move data to / from this pool and the spinning disk pools.
> 
> Given all that … would you configure those disks as 6 RAID 1 mirrors and have 6 different primary NSD servers or would it be feasible to configure one big RAID 6 LUN?  I’m thinking the latter is not a good idea as there could only be one primary NSD server for that one LUN, but given that:  1) I have no experience with this, and 2) I have been wrong once or twice before (<grin>), I’m looking for advice.  Thanks!
> 
> —
> Kevin Buterbaugh - Senior System Administrator
> Vanderbilt University - Advanced Computing Center for Research and Education
> Kevin.Buterbaugh at vanderbilt.edu - (615)875-9633
> 
> 
> 

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