raid3 is slow

Szabó Péter matyee at mail.alba.hu
Wed Mar 28 12:25:25 UTC 2007


Yes, consumers are the disks.

# graid3 list

Geom name: nmivol
State: DEGRADED
Components: 5
Flags: NONE
GenID: 0
SyncID: 73
ID: 2396346217
Zone64kFailed: 0
Zone64kRequested: 13987
Zone16kFailed: 11189
Zone16kRequested: 28827400
Zone4kFailed: 71105
Zone4kRequested: 29207293
Providers:
1. Name: raid3/nmivol
   Mediasize: 638906845184 (595G)
   Sectorsize: 2048
   Mode: r3w3e4
Consumers:
1. Name: label/nmivol2
   Mediasize: 159726711808 (149G)
   Sectorsize: 512
   Mode: r1w1e1
   State: ACTIVE
   Flags: HARDCODED
   GenID: 0
   SyncID: 73
   Number: 1
   Type: DATA
2. Name: label/nmivol1
   Mediasize: 159726711808 (149G)
   Sectorsize: 512
   Mode: r1w1e1
   State: ACTIVE
   Flags: HARDCODED
   GenID: 0
   SyncID: 73
   Number: 0
   Type: DATA
3. Name: label/nmivol3
   Mediasize: 159726711808 (149G)
   Sectorsize: 512
   Mode: r1w1e1
   State: ACTIVE
   Flags: HARDCODED
   GenID: 0
   SyncID: 73
   Number: 2
   Type: DATA
4. Name: label/nmivol4
   Mediasize: 159726711808 (149G)
   Sectorsize: 512
   Mode: r1w1e1
   State: ACTIVE
   Flags: HARDCODED
   GenID: 0
   SyncID: 73
   Number: 3
   Type: DATA

#systat -vmstat

    4 users    Load  1.62  1.75  1.82                  Mar 28 14:24

Mem:KB    REAL            VIRTUAL                     VN PAGER  SWAP PAGER
        Tot   Share      Tot    Share    Free         in  out     in  out
Act   66488    6968   150740    11396   31172 count
All 1017076   10160975701764    16256         pages
                                                        1 zfod   Interrupts
Proc:r  p  d  s  w    Csw  Trp  Sys  Int  Sof  Flt        cow    4066 total
           1 60      9820  68312106 4237  752    1 195968 wire   1002 0: clk
                                                    79088 act     128 8: rtc
89.2%Sys   3.0%Intr  3.3%User  0.0%Nice  4.5%Idl   714076 inact    10 10: 
fxp
|    |    |    |    |    |    |    |    |    |      29068 cache  1780 11: 
ata
=============================================+>>     2104 free    573 14: 
ata
                                                       12 daefr   573 15: 
ata
Namei         Name-cache    Dir-cache                     prcfr
    Calls     hits    %     hits    %                     react
       11       10   91                                 1 pdwake
                                                     4045 pdpgs
Disks   ad0   ad1   ad2   ad3   ad6                       intrn
KB/t   8.42  8.42  8.42  8.42  5.67                113904 buf
tps     287   287   287   287  1780                   133 dirtybuf
MB/s   2.36  2.36  2.36  2.36  9.85                 69984 desiredvnodes
% busy   25    26    24    26    99                 21586 numvnodes
                                                    17495 freevnodes

I use mc to copy.

Matyee

>Szabó Péter wrote:
>
>> I have a raid3 setup with 5 consumers. it seems everything is all right, 
>> but riad is very slow imho, but i don't have any >reference.
>
>You need to give more accurate information. What are the "consumers" you
>mention? Maybe you mean the disks/components of the RAID?
>
>> Now i copy from raid3 to a single hdd 75GB data. Nothing else run, except 
>> ssh, and ftp. Before the copy my load is >0.1, after i star the copy the 
>> load is 2.92 or higher, and the machine is very slow. I think this is not 
>> normal, or is it?
>
>>Copy how? By "cp" from shell?
>
>> My config is:
>> AMD Barton 2500+ with 1GB memory.
>>
>> I stop the copy, load is 0.05, and start again, after a few seconds load 
>> is 2.02.

>Due to the way raid3 works, it's by definition more CPU-intensive than
>most other RAID levels, but it shouldn't be even remotely slow as that.
>Also, since your load is > 2, what are the other CPU intensive tasks?



More information about the freebsd-geom mailing list