On 18/11/2013 19:46, Wahid Bhimji wrote:
> On 18 Nov 2013, at 17:37, Alessandra Forti <[log in to unmask]> wrote:
>
>> On 18/11/2013 17:14, Ewan MacMahon wrote:
>>>> -----Original Message-----
>>>> From: Testbed Support for GridPP member institutes [mailto:TB-
>>>> [log in to unmask]] On Behalf Of Wahid Bhimji
>>>>
>>>> 1) Many sites have previously prefered to just have the loaded server
>>>> nodes (prev R510s)  with no expansion arrays. So perhaps there should be
>>>> an option to have that configuration.
>>>> (at Edinburgh we prefer the option with the arrays though)
>>>>
>>> We've preferred the servers at Oxford on the grounds that they cost
>>> virtually the same (IIRC, at one point an R510 was actually marginally
>>> cheaper from the portal than the equivalent disk array once you factored
>>> in the RAID controller needed to use the array), and have all sorts of
>>> minor advantages.
>>>
>>>> 3) 64G RAM is quite a lot - but maybe it doesn't really change the cost.
>>>>
>>> I'd say it's actually a little short for a box of this spec - our recent
>>> machines have been 30TB usable with either 24 or 32GB of memory, so
>>> roughly speaking, on the order of 1GB of RAM per 1TB of disk. Dave's
>>> example spec would have 120TB of disk, so with 64GB of RAM it's about
>>> half that ratio. On DPM disk servers, the RAM is basically all read cache,
>>> so it's nice to have.
>> Manchester is getting away with much less than this, but direct IO might change things. Wahid never sent his pros and cons.
>>
> Well when I was referring to pros and cons that was more about current atlas configuration issues.
Well when I asked you I specified it would have been useful for the 
procurement.
> Longer term I think theres only pros - the main one being it allows for much longer analysis jobs. Increased core counts is just going to mean more pressure on WN disk(s)….
> But people are doing direct access now with their current hardware so I don't think it needs any radical changes.
which sites? what configuration? Manchester so far could get away with 
16GB/60TB on most machines. As I said direct IO might change this.

cheers
alessandra
> On the RAM - its good point, Ewan that more the merrier really - maybe I should get some more for our current disk servers.
>
> Wahid
>
>
>
>> cheers
>> alessandra
>>>> 4) Disk options: just looking at the dell normal prices - 3TB sata is
>>>> listed at 386 while 4 TB NL sas is 605. which is quite a lot more. Anyway
>>>> we maybe need to double check which offers the best value.
>>>>
>>> Indeed; our approach has been that this choice is up to the vendor to
>>> decide which approach is the cheapest overall, but based on what we've
>>> seen so far (that is, indicative hints, not formal tender responses) it
>>> does seem that having more machines with 3TB disks works our slightly ahead
>>> of a fewer boxes with 4TB disks option.
>>>
>>>> 6) Also warranty can be expensive and ought to be specified e.g. 4 yr pro
>>>> support.
>>>>
>>> We've been buying five year warranties on everything for a while - it adds
>>> trivially to the cost, and avoids the risk of having to write a machine off
>>> prematurely for want of something trivial like a PSU. And given recent trends
>>> in both our kit retirement schedule, and the (lack of) increase in disk
>>> capacities, I would confidently expect storage servers to have a life of at
>>> least five years, probably more like 7-8.
>>>
>>> All that said, my main feeling about this is that it would have been a good
>>> idea if we'd done it earlier, but it's too late now given that most of us
>>> have had the spend shifted from a planned FY14 to FY-blind-panic-do-it-now.
>>>
>>> Ewan
>>
>> -- 
>> Facts aren't facts if they come from the wrong people. (Paul Krugman)
>>
>


-- 
Facts aren't facts if they come from the wrong people. (Paul Krugman)