RE: raid0 and iscsi

[jshankar <jshankar@CS.ColoState.EDU>]

Hello Neil/Rob,

I am using IP based network(2 Intel Ethernet card Pro 1000/T).
CPUinfo is as below
:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 8
model name      : Pentium III (Coppermine)
stepping        : 1
cpu MHz         : 526.186
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov
pat pse36 mmx fxsr sse
bogomips        : 1044.22



Can u please explain me  about the below fuctionality:
2>If my chunk size is 8 byte. Does that mean it will write 8 byte into device 
0
and then into device 1. Is the write request to the disk in synchronous or
asynchronous mode.

3> Is wite_disk_sb in md.c responsible for writing into disk??. Is fsync_dev
responsible for synhronous write ??. If so can i change to asynchronous 
write.I
will really appreciate if somebody can tell me what all routines I need to go
through to figure out the functionality of raid0 behaviourand how it write to 
disk.


Thanks
Jay






===== Original Message From rob <rob@fantinibakery.com> =====
>Hello,
> What kind of network are you uasing for the data transfer?
>
> The rest of post does not answer your specific questions, but is to
>show the transfer speeds on our network to backup servers using hardware
>and software raid.
>
> Both systems use Mandrake 9.1.  network is a fast-lan. speed 100.
>
>Bkup1 is scsi with Mylex hardware raid, athlon 1800 cpu.  array has 4
>9-gb lvd disks.
>
>Bkup2 is a new test server using software raid.  dual 750 intel xeon,
>4- 9-gb se scsi disks.
>
> I transfer data 30-40 times per day to each server.  500-mb hourly on
>the average. ususal tme is less than a min.
> The test uses rsync to transfer data.  rsync uses a lot of cpu so the
>speed difference may be more due to cpu than the difference of raid type.
>
> the command used: rsync -e ssh -a --stats  /bkup3/  fbc5:/bkup3/
>
>here is the result of sending approx 3-gb of data to each:
>
>-------------------------------------------------
> this is the output of an rsync transfer to the backup software-raid server:
>
>Mon Oct 13 07:36:41 EDT 2003
>rsync[21832] (sender) heap statistics:
>  arena:        7996056   (bytes from sbrk)
>  ordblks:           59   (chunks not in use)
>  smblks:             2
>  hblks:              1   (chunks from mmap)
>  hblkhd:        516096   (bytes from mmap)
>  usmblks:            0
>  fsmblks:           80
>  uordblks:     7821736   (bytes used)
>  fordblks:      174320   (bytes free)
>  keepcost:      128840   (bytes in releasable chunk)
>
>Number of files: 65699
>Number of files transferred: 45739
>Total file size: 2707740663 bytes
>Total transferred file size: 2707630760 bytes
>Literal data: 2707630760 bytes
>Matched data: 0 bytes
>File list size: 1,925,417
>Total bytes written: 2,711,680,565
>Total bytes read: 731844
>
>wrote 2711680565 bytes  read 731844 bytes  5,046,348.67 bytes/sec
>total size is 2707740663  speedup is 1.00
>Mon Oct 13 07:45:38 EDT 2003
>
>------------------------------------
>to the hardware raid server:
>Mon Oct 13 07:23:19 EDT 2003
>rsync[19963] (sender) heap statistics:
>  arena:        7996056   (bytes from sbrk)
>  ordblks:           59   (chunks not in use)
>  smblks:             2
>  hblks:              1   (chunks from mmap)
>  hblkhd:        516096   (bytes from mmap)
>  usmblks:            0
>  fsmblks:           80
>  uordblks:     7821736   (bytes used)
>  fordblks:      174320   (bytes free)
>  keepcost:      128840   (bytes in releasable chunk)
>
>Number of files: 65699
>Number of files transferred: 45739
>Total file size: 2707740663 bytes
>Total transferred file size: 2707630760 bytes
>Literal data: 2707630760 bytes
>Matched data: 0 bytes
>File list size: 1925417
>Total bytes written: 2,711,680,565
>Total bytes read: 731844
>
>wrote 2711680565 bytes  read 731844 bytes  8,384,582.41 bytes/sec
>total size is 2707740663  speedup is 1.00
>Mon Oct 13 07:28:42 EDT 2003
>
>
>----------------
>
>
>
>Jayshankar Nair wrote:
>
>>Hello,
>>
>>
>>I was testing the raid0 configuration for the iscsi device ( /dev/sdb and
>>/dev/sdc).
>>
>>For writing a 512MB in a LAN environment it was taking 24 hrs. i was going
>>through the source code of raid0.c and certain things doesn't made sense to 
me.
>>
>>1> what role does the Hash bit play.
>>2>If my chunk size is 8 byte. Does that mean it will write 8 byte into 
device 0
>>and then into device 1. Is the write request to the disk in synchronous or
>>asynchronous mode.
>>
>>
>>3> Is wite_disk_sb in md.c responsible for writing into disk??. Is fsync_dev
>>responsible for synhronous write ??. If so can i change to asynchronous 
write.I
>>will really appreciate if somebody can tell me what all routines I need to 
go
>>through to figure out the functionality of raid0 behaviour.
>>
>>Thanks
>>Jayshankar
>>
>>-
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>>
>
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