Re: RAID 0 not as fast as expected

Greg, Josh,

Something I found out while doing this - lvm (and lvm2) slows the block
stream down dramatically. At first I was using it for convenience sake to
implement partitions on top of the md devices, but I found I was stuck at
about 700 MB/s. Removing lvm2 from the picture allowed me to get within
chucking distance of 2GB/s.

When we first started working with Solaris ZFS, we were getting about
400-600 MB/s, and after working with the Solaris Engineering team we now get
rates approaching 2GB/s. The updates needed to Solaris are part of the
Solaris 10 U3 available in October (and already in Solaris Express, aka
Solaris 11).

- Luke

On 9/15/06 5:43 AM, "Spiegelberg, Greg" <gspiegelberg(at)cranel(dot)com> wrote:

> That's an all PCI-X box which makes sense. There are 6 SATA controllers
> in that little beastie also. You can always count on Sun to provide
> over engineered boxes.
>
>
>
>> -----Original Message-----
>> From: pgsql-performance-owner(at)postgresql(dot)org
>> [mailto:pgsql-performance-owner(at)postgresql(dot)org] On Behalf Of
>> Joshua D. Drake
>> Sent: Friday, September 15, 2006 12:01 AM
>> To: Luke Lonergan
>> Cc: Craig A. James; pgsql-performance(at)postgresql(dot)org
>> Subject: Re: [PERFORM] RAID 0 not as fast as expected
>>
>> Luke Lonergan wrote:
>>> Josh,
>>>
>>> On 9/14/06 8:47 PM, "Joshua D. Drake" <jd(at)commandprompt(dot)com> wrote:
>>>
>>>>> I've obtained 1,950 MB/s using Linux software RAID on SATA drives.
>>>> With what? :)
>>>
>>> Sun X4500 (aka Thumper) running stock RedHat 4.3 (actually
>> CentOS 4.3)
>>> with XFS and the linux md driver without lvm. Here is a
>> summary of the results:
>>>
>>
>>
>> Good god!
>>
>>>
>>> Read Test
>>> RAID Level Max Readahead (KB) RAID Chunksize Max Readahead
>> on Disks
>>> (KB) Max Time (s) Read Bandwidth (MB/s) 0 65536 64 256 16.689
>>> 1,917.43 0 4096 64 256 21.269 1,504.54 0 65536 256 256 17.967
>>> 1,781.04 0 2816 256 256 18.835 1,698.96 0 65536 1024 256 18.538
>>> 1,726.18 0 65536 64 512 18.295 1,749.11 0 65536 64 256 18.931
>>> 1,690.35 0 65536 64 256 18.873 1,695.54 0 64768 64 256 18.545
>>> 1,725.53 0 131172 64 256 18.548 1,725.25 0 131172 64
>> 65536 19.046
>>> 1,680.14 0 131172 64 524288 18.125 1,765.52 0 131172 64 1048576
>>> 18.701 1,711.14
>>> 5 2560 64 256 39.933 801.34
>>> 5 16777216 64 256 37.76 847.46
>>> 5 524288 64 256 53.497 598.16
>>> 5 65536 32 256 38.472 831.77
>>> 5 65536 32 256 38.004 842.02
>>> 5 65536 32 256 37.884 844.68
>>> 5 2560 16 256 41.39 773.13
>>> 5 65536 16 256 48.902 654.37
>>> 10 65536 64 256 83.256 384.36
>>> 1+0 65536 64 256 19.394 1,649.99
>>> 1+0 65536 64 256 19.047 1,680.05
>>> 1+0 65536 64 256 19.195 1,667.10
>>> 1+0 65536 64 256 18.806 1,701.58
>>> 1+0 65536 64 256 18.848 1,697.79
>>> 1+0 65536 64 256 18.371 1,741.88
>>> 1+0 65536 64 256 21.446 1,492.12
>>> 1+0 65536 64 256 20.254 1,579.93
>>>
>>>
>>
>>
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>