[svlug] New server plans moving forward

Jeff Frost jeff at frostconsultingllc.com
Sun Jan 21 19:24:27 PST 2007


On Sun, 21 Jan 2007, Rick Moen wrote:

> RAID 0+1 or RAID 1+0 also yields faster disk I/O, but we don't really
> benefit from that (because Web/mail servers are typically much more
> constrained by network I/0 or RAM, than by disk I/0).

Actually, RAID5 generally has faster block read access, but raid 10 has better 
block write access.  Raid10 also tends to do better with multiple processes 
reading from it as it can round robin the reads from different drives in the 
raid1 pairs.  But that's controller dependent.  I'm not sure if md does that 
or not.

Mail servers tend to do quite a bit of writing depending on how many users 
they support, but I suspect either array will be performant enough for the 
needs.

Just as an FYI, here are some bonnie++ results from a Dual Opteron system with 
an Areca 1130 SATA RAID controller with 1GB of battery backed cache.  As 
you'll see from these results, the RAID5 actually outperforms the RAID10 on 
reads and writes, though not by that much in some of the tests.

Bottom line:
RAID 5 avg block writes: 165MB/s
RAID10 avg block writes: 155MB/s

RAID 5 avg block reads: 360MB/s
RAID10 avg block reads: 304MB/s

We ended up going with the RAID 10 because our real world benchmarks showed 
the two much closer in the end and RAID10 gives us more reliability.  I 
attribute much of RAID5's excellent write performance to the battery backed 
cache on the controller.

Here's the raw data:

Version  1.03      ------Sequential Output------ --Sequential Input- --Random-
                     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
8xRAID5         16G 47345  96 166696  65 92560  25 53485  91 344003  39 429.1   1
8xRAID5         16G 47155  95 156793  60 93368  25 54081  91 342959  39 425.7   1
8xRAID5         16G 48639  99 109607  45 93313  25 54416  91 343931  39 482.7   1
8xRAID5         16G 48339  99 165683  67 93130  26 53972  91 346083  39 486.7   1
8xRAID5         16G 52341  98 147712  61 82333  22 54480  91 347725  38 545.2   1
8xRAID5         16G 52342  98 168912  66 92977  25 54501  91 347088  39 550.8   1
8xRAID5         16G 48535  99 171709  71 93491  26 54395  91 345852  39 560.8   1
8xRAID5         16G 48911  99 177653  68 94608  26 53683  91 348030  39 554.2   1
8xRAID5         16G 52641  98 172885  70 92058  26 54766  91 348429  38 559.3   1
8xRAID5         16G 51691  96 176042  68 94463  25 54275  91 350535  38 561.2   1
8xRAID5         16G 47740  96 156260  58 94484  26 53656  91 372554  44 402.8   1
8xRAID5         16G 48042  96 138879  54 66346  19 54443  91 373442  43 515.1   1
8xRAID5         16G 49055  99 174354  64 95937  27 54620  91 376324  43 523.5   1
8xRAID5         16G 49036  99 168503  63 97576  28 54314  91 374909  42 533.0   1
8xRAID5         16G 51632  96 185940  69 96046  27 54476  91 376895  43 553.4   1
8xRAID5         16G 53446  99 173056  62 98185  27 54809  91 376554  42 573.0   1
8xRAID5         16G 49279  99 185841  70 95939  26 54483  91 377040  43 555.0   1
8xRAID5         16G 49655  99 176175  66 95725  27 53810  91 374488  42 548.6   1
8xRAID5         16G 53346  99 157177  61 93846  26 54843  91 376606  43 567.4   1
8xRAID5         16G 52566  97 179388  67 97473  28 54309  91 375667  42 532.3   1
8xRAID10        16G 44826  92 133985  49 84948  23 53577  90 303047  34 426.5   1
8xRAID10        16G 46572  96 139745  54 87086  23 53296  90 303582  36 422.8   1
8xRAID10        16G 46824  96 139979  53 86080  24 53500  90 303702  34 429.5   1
8xRAID10        16G 46902  96 149656  58 85879  23 53503  90 302190  35 425.1   1
8xRAID10        16G 52251  98 138883  53 86957  23 53627  90 298891  34 423.9   1
8xRAID10        16G 51902  97 147934  55 85965  23 53340  90 302296  35 424.8   1
8xRAID10        16G 46832  95 137151  53 88663  24 53239  90 303494  35 443.5   1
8xRAID10        16G 46753  96 147849  57 85808  23 53777  91 303251  35 466.2   1
8xRAID10        16G 52075  98 148951  58 86290  23 53975  91 302604  34 469.1   1
8xRAID10        16G 52326  98 169924  65 84225  23 54450  91 303258  35 474.3   1
8xRAID10        16G 44216  92 144170  55 82654  23 52736  89 308019  37 342.6   1
8xRAID10        16G 47675  98 164628  65 88821  25 52703  88 307788  35 520.9   1
8xRAID10        16G 48156  98 171730  65 87921  24 52436  88 306042  35 506.7   1
8xRAID10        16G 52499  98 175165  68 85904  23 53181  89 306815  35 520.3   1
8xRAID10        16G 52687  98 170289  63 88227  24 52410  88 307389  35 536.1   1
8xRAID10        16G 47617  98 175288  70 87934  24 52631  88 305520  35 517.1   1
8xRAID10        16G 47576  98 172533  71 87157  24 52358  88 307704  35 518.4   1
8xRAID10        16G 52054  98 151720  58 86400  24 53051  89 308187  35 527.3   1
8xRAID10        16G 52672  99 169353  68 87984  25 52748  88 307422  35 537.9   1
                     ------Sequential Create------ --------Random Create--------
                     -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files:max:min        /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
8xRAID5          16   894   0 +++++ +++   841   0   909   0 +++++ +++   913   0
8xRAID5          16   907   0 +++++ +++   879   0   866   0 +++++ +++   830   0
8xRAID5          16   912   0 +++++ +++   870   0   909   0 +++++ +++   873   0
8xRAID5          16   907   0 +++++ +++   838   0   871   0 +++++ +++   879   0
8xRAID5          16   906   0 +++++ +++   867   0   940   0 +++++ +++   862   0
8xRAID5          16   900   0 +++++ +++   884   0   882   0 +++++ +++   826   0
8xRAID5          16   908   0 +++++ +++   867   0   869   0 +++++ +++   875   0
8xRAID5          16   914   0 +++++ +++   878   0   887   0 +++++ +++   883   0
8xRAID5          16   892   0 +++++ +++   878   0   910   0 +++++ +++   836   0
8xRAID5          16   897   0 +++++ +++   842   0   895   0 +++++ +++   879   0
8xRAID5          16   904   0 +++++ +++   929   0   908   0 +++++ +++   834   0
8xRAID5          16   895   0 +++++ +++   855   0   905   0 +++++ +++   881   0
8xRAID5          16   869   0 +++++ +++   892   0   926   0 +++++ +++   882   0
8xRAID5          16   928   0 +++++ +++   879   0   871   0 +++++ +++   835   0
8xRAID5          16   907   0 +++++ +++   879   0   871   0 +++++ +++   831   0
8xRAID5          16   934   0 +++++ +++   847   0   882   0 +++++ +++   867   0
8xRAID5          16   888   0 +++++ +++   832   0   917   0 +++++ +++   917   0
8xRAID5          16   943   0 +++++ +++   885   0   909   0 +++++ +++   881   0
8xRAID5          16   884   0 +++++ +++   835   0   923   0 +++++ +++   907   0
8xRAID5          16   870   0 +++++ +++   879   0   948   0 +++++ +++   873   0
8xRAID10         16   869   0 +++++ +++   878   0   952   0 +++++ +++   871   0
8xRAID10         16   906   0 +++++ +++   867   0   923   0 +++++ +++   884   0
8xRAID10         16   869   0 +++++ +++   839   0   908   0 +++++ +++   876   0
8xRAID10         16   908   0 +++++ +++   856   0   870   0 +++++ +++   851   0
8xRAID10         16   901   0 +++++ +++   908   0   884   0 +++++ +++   877   0
8xRAID10         16   904   0 +++++ +++   838   0   869   0 +++++ +++   873   0
8xRAID10         16   906   0 +++++ +++   862   0   859   0 +++++ +++   854   0
8xRAID10         16   933   0 +++++ +++   880   0   910   0 +++++ +++   832   0
8xRAID10         16   869   0 +++++ +++   879   0   944   0 +++++ +++   875   0
8xRAID10         16   941   0 +++++ +++   861   0   891   0 +++++ +++   878   0
8xRAID10         16   918   0 +++++ +++   845   0   907   0 +++++ +++   875   0
8xRAID10         16   909   0 +++++ +++   839   0   879   0 +++++ +++   861   0
8xRAID10         16   889   0 +++++ +++   885   0   922   0 +++++ +++   876   0
8xRAID10         16   901   0 +++++ +++   877   0   876   0 +++++ +++   833   0
8xRAID10         16   870   0 +++++ +++   884   0   950   0 +++++ +++   875   0
8xRAID10         16   906   0 +++++ +++   855   0   901   0 +++++ +++   855   0
8xRAID10         16   905   0 +++++ +++   917   0   909   0 +++++ +++   828   0
8xRAID10         16   896   0 +++++ +++   819   0   904   0 +++++ +++   873   0
8xRAID10         16   904   0 +++++ +++   926   0   908   0 +++++ +++   876   0


-- 
Jeff Frost, Owner 	<jeff at frostconsultingllc.com>
Frost Consulting, LLC 	http://www.frostconsultingllc.com/
Phone: 650-780-7908	FAX: 650-649-1954




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