From: Heinz Mauelshagen <mauelsha@ez-darmstadt.telekom.de>
To: Hans-Joachim Baader <hans@grumbeer.inka.de>
Cc: mge@ez-darmstadt.telekom.de, linux-lvm@msede.com
Subject: [linux-lvm] Re: LVM bug report and questions
Date: Sun, 5 Mar 2000 18:07:22 +0100 (MET) [thread overview]
Message-ID: <200003051707.SAA31929@u9etz.ez-darmstadt.telekom.de> (raw)
In-Reply-To: <m12Rayn-0006h9C@grumbeer.inka.de> from Hans-Joachim Baader at "Mar 5, 2000 2:21:53 pm"
> Hi,
>
> I have kernel 2.2.15pre13, LVM 0.7 (first question: will 0.8 be ported
> to kernel 2.2.15?
Yes.
) on a dual Pentium-200 MMX with two 20G IBM disks
> (/dev/hdb and /dev/hdc at the moment).
> vgscan was unable to find the volume groups I defined. In the debug
> output I could see that after scanning hda16, the scan continued
> with hdb11 rather than hdb1. I found the relevant code which looked
> suspicous to me. So I changed it:
>
> --- pv_read_all_pv.c.orig Sun Mar 5 14:07:34 2000
> +++ pv_read_all_pv.c Sun Mar 5 14:07:40 2000
> @@ -102,7 +102,7 @@
> if ( ( tst = open ( dev_name, O_RDONLY)) == -1) {
> if ( MAJOR ( dir_cache[n].st_rdev) != MD_MAJOR &&
> MINOR ( dir_cache[n].st_rdev) % 16 == 0) {
> - n += 15;
> + /*n += 15;*/
> continue;
> }
> } else close ( tst);
>
> It's probably still wrong but at least it worked for me ;-)
In some /dev configurations there's overlapping of device nodes which
breaks the above performance oriented search algorithm.
Your workaround helps in these cases as correct setup of all /dev
nodes does.
>
> It is possible to make a LV the root partition if initrd is used.
> However, is this also possible when the root is on a striped LV?
Yes.
> I guess not because LILO would have to know how to handle it.
LILO loads an initrd from a small partition (about 20MB in size)
and at the EOF of /linuxrc after activation of the Volume Group(s)
it switches to the real root-filesystem which can live on a
striped logical volume,
> Are there plans to make this possible?
See above.
>
> What is the performance of striped LVs compared to a md device with
> RAID0?
More or less the same.
> On my system, using Reiserfs, I get about 9 MB/s on each
> individual disk, measured with hdparm. On a striped LV I get
> about 11 MB/s, measured with Bonnie.
Do you have all Physical Volumes you use to allocate Extemts to the striped
Logical Volume on different physical disks and IDE adapters?
> Given that hdparm and Bonnie
> usually agree about the speed, this seems not much of an
> improvement. How much is the CPU overhead for striped LVs?
Minimal.
> Is there more to gain in different configurations, eg. if I
> hooked the disks to a UDMA controller?
>
> Thanks,
> hjb
> --
> http://www.pro-linux.de/ - Germany's largest volunteer Linux support site
> You feel strangely lucky...
>
Heinz
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Systemmanagement CS-TS T-Nova
Entwicklungszentrum Darmstadt
Heinz Mauelshagen Otto-Roehm-Strasse 71c
Senior Systems Engineer Postfach 10 05 41
64205 Darmstadt
mge@EZ-Darmstadt.Telekom.de Germany
+49 6151 886-425
FAX-386
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
parent reply other threads:[~2000-03-05 17:07 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <m12Rayn-0006h9C@grumbeer.inka.de>]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200003051707.SAA31929@u9etz.ez-darmstadt.telekom.de \
--to=mauelsha@ez-darmstadt.telekom.de \
--cc=hans@grumbeer.inka.de \
--cc=linux-lvm@msede.com \
--cc=mge@ez-darmstadt.telekom.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.