Disk Access Seems Slow in 5.4

[Drew Tomlinson]

I have two boxes running FBSD.  One is an old AMD 350 mhz machine with 
just 128 MB of RAM and a 4 GB IDE drive that's attached to a 33mhz 
controller.  The other is a dual Pentium 600 machine with 768 MB RAM and 
two 9 GB SCSI drives.

Ever since I upgraded the dual Pentium from 4.11 to 5.4, disk access 
seems slower.  I can't know for sure because I never did any 
benchmarking before.  I used vinum striping in 4.x but moved to gstripe 
in 5.4.  I notice it most when using an IMAP client to connect to 
Courier on this 5.4 machine.  So maybe it's just slow with small files?  
Here's my 'gstripe list' output so you can see how the stripe set is built:

--- BEGIN ---
blacklamb# gstripe list
Geom name: data
State: UP
Status: Total=2, Online=2
Type: AUTOMATIC
Stripesize: 131072
ID: 1477809630
Providers:
1. Name: stripe/data
   Mediasize: 17160732672 (16G)
   Sectorsize: 512
   Mode: r1w1e0
Consumers:
1. Name: da1s1d
   Mediasize: 8580481024 (8.0G)
   Sectorsize: 512
   Mode: r1w1e1
   Number: 1
2. Name: da0s1d
   Mediasize: 8580481024 (8.0G)
   Sectorsize: 512
   Mode: r1w1e1
   Number: 0
--- END ---


I really don't know what to check or how to go about checking it.  I 
Googled and found that bonnie++ seems to be popular.  Another is 
postmark.  I installed these tools and ran them both on my 5.4 server 
with the SCSI drives and the 4.11 server with the slow 33mhz IDE drive 
in it.  Using default settings, postmark shows the 5.4 box about 2 1/2 
times slower than the 4.11 box.


--- BEGIN 5.4 Box ---
Creating files...Done
Performing transactions..........Done
Deleting files...Done
Time:
        24 seconds total
        9 seconds of transactions (55 per second)

Files:
        764 created (31 per second)
                Creation alone: 500 files (100 per second)
                Mixed with transactions: 264 files (29 per second)
        243 read (27 per second)
        257 appended (28 per second)
        764 deleted (31 per second)
                Deletion alone: 528 files (52 per second)
                Mixed with transactions: 236 files (26 per second)

Data:
        1.36 megabytes read (58.22 kilobytes per second)
        4.45 megabytes written (189.70 kilobytes per second)
--- END 5.4 Box ---

--- BEGIN 4.11 Box ---
pm>run
Creating files...Done
Performing transactions..........Done
Deleting files...Done
Time:
        10 seconds total
        4 seconds of transactions (125 per second)

Files:
        764 created (76 per second)
                Creation alone: 500 files (100 per second)
                Mixed with transactions: 264 files (66 per second)
        243 read (60 per second)
        257 appended (64 per second)
        764 deleted (76 per second)
                Deletion alone: 528 files (528 per second)
                Mixed with transactions: 236 files (59 per second)

Data:
        1.36 megabytes read (139.72 kilobytes per second)
        4.45 megabytes written (455.28 kilobytes per second)
--- END 4.11 Box ---

I also ran bonnie++ on both boxes  Here's ouput from the 5.4 box

Version 1.93c       ------Sequential Output------ --Sequential Input- 
--Random-
Concurrency   1     -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
blacklamb      300M    39  99  9115  18  8273  20   107  99 112354  99  
2306 207
Latency               329ms     129ms     314ms     150ms    1557us    
2365ms
Version 1.93c       ------Sequential Create------ --------Random 
Create--------
blacklamb           -Create-- --Read--- -Delete-- -Create-- --Read--- 
-Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  
/sec %CP
                 16    75   3 19237  99   116   3    75   3 19069  99   
185   6
Latency               384ms     212us     260ms     209ms     662us     
464ms

And here's from the 4.11 box:

Version 1.93c       ------Sequential Output------ --Sequential Input- 
--Random-
Concurrency   1     -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
blacksheep     300M    47  96  4262   8  1954   5   101  96  4442   5  
68.2   5
Latency               705ms     532ms     442ms     265ms     291ms    
9196ms
Version 1.93c       ------Sequential Create------ --------Random 
Create--------
blacksheep          -Create-- --Read--- -Delete-- -Create-- --Read--- 
-Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  
/sec %CP
                 16  3806  62 12911  78  9469  91  3644  57 15577  99  
2940  29
Latency               342ms   13128us     658us     247ms     644us     
714ms

I don't really know what all of this means.  However the 4.11 box 
finished both tests much faster than the 5.4 box.  Thus it seems I have 
a drive performance issue.  What should I do to improve performance on 
the 5.4 box?  I'm getting ready to upgrade to 6.0 and see this as an 
opportunity to modify the disk parameters if needed.

Thanks,

Drew

-- 
Visit The Alchemist's Warehouse
Magic Tricks, DVDs, Videos, Books, & More!

http://www.alchemistswarehouse.com