Little Things Doth Crabby Make Part I. Enterprise Linux 5/RHEL5 Output Format Change for the iostat Command

Yes, I admit, sometimes little things make me crabby. Or is it that being crabby makes me easily irritated at small things? I think it’s the former rather than the latter.

Angry Email Makes Me Crabby
I am surprised at how many emails I’ve received from angry Storage Administrators about my position against Fibre Channel. I generally just ask them to not take it so personally. After all, there is more to storage than whatever storage networking protocol any particular server is plumbed with. Anyone who reads my Manly Man series about Fibre Channel will see that I’m just not a big fan of the current misapplication of Fibre Channel technology. As I point out in installment number two in the Manly Man series, Fibre Channel was originally intended to solve the difficulties associated with connecting hundreds (or thousands) of low capacity drives to a small number of large servers. These days it is being used to provide storage connectivity for hundreds of servers to a couple of huge FC storage arrays. And these hundreds of servers have both Ethernet and FC connectivity-overkill, plain and simple.

A lot is changing in the storage world where Oracle is concerned. I hope to come out of the foxhole to blog more about it over the next few months. Well, maybe I should say a few months from now. In the meantime I’ll be making some datacenter visits. I always learn something interesting when I get a chance to do that.

Little Changes Make Me Crabby
Like, for instance, the following example of the change to iostat -x output from RHEL4 to RHEL5. Notice how the rkB/s and wkB/s columns are missing? Yes, it is simple math to divide [rw]sec/s by 2 to get the same data, but there must be at least 42 of you folks that are feeding iostat -x output through some text processing, right? Time to adjust your scripts. Or is it? I wonder how many folks are really diving into OEL5/RHEL5? It seems a conservative IT shop with a functional RHEL4 configuration would most likely stay put. Any readers care to voice their experience with OEL5/RHEL5 adoption? Is it happening? Are folks waiting for their 11g adoption with plans to team that up with a move to OEL5/RHEL5?

# uname -r
# iostat -x 1 1
Linux 2.6.18-53.el5 (host1)        03/07/2008

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.08    0.00    0.04    0.03    0.00   99.85

Device:         rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
cciss/c0d0        0.16    10.38  0.33  0.95    10.55    90.64    79.47     0.02   14.12   0.86   0.11
sda               0.00     0.00  0.00  0.00     0.01     0.00    21.05     0.00    3.18   2.87   0.00
dm-0              0.00     0.00  0.45 11.33    10.47    90.64     8.58     0.39   32.67   0.09   0.11
dm-1              0.00     0.00  0.00  0.00     0.01     0.00     8.00     0.00    5.05   0.51   0.00
cciss/c0d1        0.00     0.00  0.00  0.00     0.01     0.00    10.12     0.00    4.56   2.63   0.00
cciss/c0d2        0.00     0.00  0.00  0.00     0.01     0.00    10.38     0.00    4.30   2.52   0.00
cciss/c0d3        0.00     0.00  0.00  0.00     0.01     0.00    10.38     0.00    6.17   3.35   0.00
cciss/c0d4        0.00     0.00  0.00  0.00     0.01     0.00    10.38     0.00    5.50   3.22   0.00
cciss/c0d5        0.00     0.00  0.00  0.00     0.01     0.00    10.64     0.00    3.38   2.59   0.00
cciss/c0d6        0.00     0.00  0.00  0.00     0.01     0.00    10.64     0.00    4.05   3.31   0.00
cciss/c0d7        0.00     0.00  0.00  0.00     0.01     0.00    10.12     0.00    4.44   2.29   0.00

$ uname -r
$ iostat -x 1 1
Linux 2.6.9-34.ELsmp (host2)    03/07/2008

avg-cpu:  %user   %nice    %sys %iowait   %idle
           1.79    0.00    1.28    0.30   96.63

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
cciss/c0d0   0.06  11.83  0.14  3.21   23.07  120.39    11.53    60.19    42.77     0.68  201.33   4.60   1.54

4 Responses to “Little Things Doth Crabby Make Part I. Enterprise Linux 5/RHEL5 Output Format Change for the iostat Command”

  1. 1 Luke Youngblood March 15, 2008 at 12:10 am

    Your blog is great and very interesting. Here is my experience. I’m a Linux sysadmin (not a DBA) but all I do is Oracle RAC support for our DBA team.

    We’ve used Redhat 5 and 11g on a single test server, but our head DBA says we’re holding off on it because Oracle hasn’t yet certified Grid Agent as compatible with Redhat 5.

    I’m deploying 3 brand new 4-node clusters on Sun Fire X4600 (8 way Opteron baby!) with EVA 8100 storage on the back end, quad 4gb HBAs in every server, and we are going Redhat 4 Update 6 64-bit and Oracle 10gR2 all the way.

    Also, I have to say it’s a major pain in the ass how they deprecated the /etc/sysconfig/rawdevices interface. It was easy to configure before and now it’s just a pain in the ass.

    Well, I’m sure Redhat 5 will be nice eventually, but for now, all we get is:

    1. A scheduler in the new kernel that is not very database friendly (Completely Fair Scheduler is nice for desktop Linux but terrible for database).

    2. Built in virtualization (woohoo! Now my single purpose Oracle box has the capability of running more than one OS, which it will never do…)

    3. A deprecated rawdevices interface that makes life difficult for Oracle DBAs and sysadmins.

    4. And as you mentioned, all of my performance monitoring scripts that pull data out of iostat and INSERT it into a table have to be modified.


    Keep up the blog, this is great stuff.

  2. 2 Alex Gorbachev March 22, 2008 at 1:35 am

    Luke, I wish all SA’s would be more like you.
    Not many SA’s are reading Oracle blogs. 🙂

    Re: raw devices. With 10gR2 you need to configure raw devices only during installation of CRS – voting disks and OCR. After upgrade to, I always get rid of raw devices and use block devices directly. They are opened with O_DIRECT. I like to exclude unnecessary layers and raw devices is a good example.

  3. 3 kevinclosson March 22, 2008 at 5:08 am

    Opening a raw device (raw(8)) with open is the same thing as opening a block device with open(O_DIRECT). There is no “there” there.

    …thanks for stopping by Alex…as always.

  1. 1 Little Things Doth Crabby Make Part III. Non-Erroring Errors and Erroneous Experiments. « Kevin Closson’s Oracle Blog: Platform, Storage & Clustering Topics Related to Oracle Databases Trackback on March 28, 2008 at 7:31 pm

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