[CentOS] slow responding firewall server

[Peter Farrow]

No,

hdparm -t gives you the uncached speed, -T gives you the cached speed:
hdparm -Tt /dev/hda

/dev/hda:
 Timing cached reads:   472 MB in  2.00 seconds = 235.68 MB/sec
 Timing buffered disk reads:   62 MB in  3.06 seconds =  20.23 MB/sec

hdparm -Tt /dev/hdb

/dev/hdb:
 Timing cached reads:   480 MB in  2.00 seconds = 239.80 MB/sec
 Timing buffered disk reads:   62 MB in  3.03 seconds =  20.46 MB/sec


The disks are set the logical block assignments already, and anaconda, 
detects the number of cylinders differently in the install, which makes 
mirroring non symmetrical, trust me when on channel 1 and 2, I've 
checked this in great detail, furthermore, simultaneous requests to both 
drives isn't affecting performance as much as you imagine, here are the 
results of a simultaneous hdparm test:

 Timing cached reads:    Timing cached reads:   272 MB in  2.01 seconds 
= 135.08 MB/sec
340 MB in  2.01 seconds = 168.76 MB/sec
 Timing buffered disk reads:   Timing buffered disk reads:   46 MB in  
3.08 seconds =  14.93 MB/sec
 46 MB in  3.08 seconds =  14.92 MB/sec

[5]-  Done                    hdparm -Tt /dev/hda
[6]+  Done                    hdparm -Tt /dev/hdb


Also the old machine had them on the same channel two for the same reason.....

This isn't the issue, its something else.......

P.



Bryan J. Smith wrote:

>Peter Farrow <peter at farrows.org> wrote:
>  
>
>>[root@ ~]# hdparm -t /dev/hdb
>>/dev/hdb:
>> Timing buffered disk reads:   62 MB in  3.07 seconds = 
>>20.17 MB/sec
>>[root@ ~]# hdparm -t /dev/hda
>>/dev/hda:
>> Timing buffered disk reads:   62 MB in  3.02 seconds = 
>>20.51 MB/sec
>>    
>>
>
>Ouch!  They are on the same channel!  Furthermore, you're
>only getting the cache speed.  Try "-Tt" instead.  And try
>running those 2 commands simultaneously!  You're going to see
>more than a 50% drop (more like an 80%!).
>
>  
>
>> UDMA modes: udma0 udma1 *udma2 udma3 udma4 udma5
>> UDMA modes: udma0 udma1 *udma2 udma3 udma4 udma5
>>    
>>
>
>Ultra DMA mode 2 (33MHz) is a good sign.
>
>  
>
>>I'm running software RAID and they are both on one IDE
>>controller, but this is because the installer detects
>>the drive geometry differently for each if they are on
>>separate controller,
>>    
>>
>
>If it's Award BIOS, then set the geometry to "LBA" in the
>BIOS.
>
>Furthermore, _regardless_ of what the BIOS says, once you
>partition with LBA, if you move it to another controller, the
>partition table will _still_ be LBA when Linux loads the
>partitions.
>
>  
>
>>which would be the best option, but as I am doing mirroring
>>    
>>
>I
>  
>
>>want the geometry the same. 
>>    
>>
>
>The geometry is _already_ the same once the partition table
>has been created.  Linux _ignores_ the BIOS' geometry if it
>was partitioned differently.
>
>  
>
>>Furthermore no amount of changing in the BIOS affects the
>>detected geometry by Anaconda.  I've seen this quite a lot
>>    
>>
>on
>  
>
>>Compaqs.
>>    
>>
>
>Oh, a Compaq.  Yeah, broken BIOS.
>
>But _regardless_, you've already got the correct geometry. 
>You can now move channels, Linux will read the partition
>table and use its geometry -- not what the BIOS says.
>
>ATA DMA was _never_ designed for master/slave, that's an old
>EIDE PIO configuration.  Drives only allow it to be
>compatible, but it's not recommended at all.
>
>
>  
>