MD1000 and PERC5/E I/O bottleneck

Eric Yablonowitz eyablon at tripadvisor.com
Mon Jun 4 09:11:31 CDT 2007


http://accessories.us.dell.com/sna/productdetail.aspx? 
c=us&l=en&s=bsd&cs=04&sku=341-4339

Tech Specs
Cache / Buffer Size	Data Transfer Rate
256 MB	Up to 3 Gbps
Device Type	Interface Type
RAID Controller Card	x8 PCI Express®
Port(s) Total ( Free ) / Connector Type	RAID Level
2 (external SAS x4)	0, 1, 5, 10, 50
Slot(s) Required	
PCI Express®	


On Jun 4, 2007, at 10:07 AM, Vincent Janelle wrote:

> I thought the perc 5/e had a 1x connector?
>
> -----Original Message-----
> From: Eric Yablonowitz [mailto:eyablon at tripadvisor.com]
> Sent: Monday, June 04, 2007 7:08 AM
> To: Vincent Janelle
> Cc: Peter Verhoeven; linux-poweredge at dell.com
> Subject: Re: MD1000 and PERC5/E I/O bottleneck
>
> Nope.  Nowhere close.  PCI-e x8 has a bandwidth of 32Gbps.
>
> http://www.dell.com/content/topics/global.aspx/vectors/en/
> 2004_pciexpress?c=us&l=en&s=corp
>
> On Jun 4, 2007, at 10:00 AM, Vincent Janelle wrote:
>
>> You're hitting the upper limits of pci-e right now, its limited to  
>> 2.5
>> gigabits per second.. I think.
>>
>> You might also want to check the block size that you're making your
>> file
>> system with, that might give you some better I/O.
>>
>> -----Original Message-----
>> From: Eric Yablonowitz [mailto:eyablon at tripadvisor.com]
>> Sent: Monday, June 04, 2007 5:32 AM
>> To: Vincent Janelle
>> Cc: Peter Verhoeven; linux-poweredge at dell.com
>> Subject: Re: MD1000 and PERC5/E I/O bottleneck
>>
>> full MD1000 w/ 15K RPM SAS HDDs.
>>
>> On Jun 4, 2007, at 12:22 AM, Vincent Janelle wrote:
>>
>>> Are these sata disks, or sas?
>>>
>>> -----Original Message-----
>>> From: linux-poweredge-bounces at dell.com
>>> [mailto:linux-poweredge-bounces at dell.com] On Behalf Of Eric
>>> Yablonowitz
>>> Sent: Sunday, June 03, 2007 6:37 PM
>>> To: Peter Verhoeven
>>> Cc: linux-poweredge at dell.com
>>> Subject: Re: MD1000 and PERC5/E I/O bottleneck
>>>
>>> RAID-1 (inherently 2 disks) offers much less write throughput than a
>>> 7 disk RAID-5 on the PERC-5 in my tests.  RAID-10 on 6 disks was
>>> closer, but still (somewhat surprisingly) slower than RAID-5 on 7
>>> disks.
>>>
>>> On Jun 3, 2007, at 9:21 PM, Peter Verhoeven wrote:
>>>
>>>> Can you afford to go with RAID-1 instead of RAID 5?
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: linux-poweredge-bounces at dell.com
>>>> [mailto:linux-poweredge-bounces at dell.com] On Behalf Of Eric
>>>> Yablonowitz
>>>> Sent: Saturday, 2 June 2007 9:03 AM
>>>> To: linux-poweredge at dell.com
>>>> Subject: MD1000 and PERC5/E I/O bottleneck
>>>>
>>>> So these results imply that there is a bottleneck somewhere that is
>>>> preventing me from getting anywhere near what my 14 spindles can
>>>> handle.
>>>> Any thoughts on what this bottleneck might be?
>>>>
>>>> Thanks,
>>>> Eric
>>>>
>>>
>>
>>
>>
>
>
>



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