From: hpa@zytor.com (H. Peter Anvin)
To: linux-raid@vger.kernel.org
Subject: Re: Call for RAID-6 users
Date: Thu, 5 Aug 2004 23:51:16 +0000 (UTC) [thread overview]
Message-ID: <ceuh5k$reo$1@terminus.zytor.com> (raw)
In-Reply-To: 200407302338.33823.maarten@ultratux.net
Followup to: <200407302338.33823.maarten@ultratux.net>
By author: maarten van den Berg <maarten@ultratux.net>
In newsgroup: linux.dev.raid
>
> On Friday 30 July 2004 23:11, maarten van den Berg wrote:
> > On Saturday 24 July 2004 01:32, H. Peter Anvin wrote:
>
> > I'm still early in the testing phase, so nothing to report as yet.
> > But I have a question: I tried to reproduce a reported issue when creating
> > a degraded raid6 array. But when I created a raid6 array with one disk
> > missing, /proc/mdstat reported no resync going on. Am I not correct in
> > assuming that raid6 with 1 missing drive should at least start resyncing
> > the other drive(s) ? It would only be really degraded with two missing
> > drives...
> >
> > So instead, I defined a full raid6 array which it is now resyncing...
> > My resync speed is rather slow (6000K/sec). I'll have to compare it to
> > resyncing a raid5 array though before concluding anything from that. Cause
> > this system is somewhat CPU challenged indeed: a lowly celeron 500.
>
> To confirm, after stopping the raid6 array (didn't want to wait this long) I
> created a raid5 array on the same machine and it resyncs at 14000K/sec.
> Is this expected behaviour, the 6M/sec for raid6 vs 14M/sec for raid5 ?
> I suppose raid6 has to sync two drives, which would maybe explain the speed
> difference(?) In any case, hdparm -tT report 50M/sec on each single drive.
> Is this discrepancy in speed normal ?
> (yes yes, I played with the /proc/sys/dev/raid/ speed settings (to no avail))
>
A newly created RAID-5 array uses a special trick to do the initial
sync faster. Unfortunately that trick is not possible for RAID-6.
-hpa
next prev parent reply other threads:[~2004-08-05 23:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-23 23:32 Call for RAID-6 users H. Peter Anvin
2004-07-26 21:38 ` Jim Paris
2004-07-27 2:05 ` Matthew - RAID
2004-07-27 2:12 ` Jim Paris
2004-07-27 16:40 ` Ricky Beam
2004-07-27 17:20 ` Jim Paris
2004-07-27 18:19 ` Jim Paris
2004-07-27 18:48 ` Jim Paris
2004-07-28 3:09 ` Jim Paris
2004-07-28 8:36 ` David Greaves
2004-07-28 10:02 ` Jim Paris
2004-07-30 15:58 ` H. Peter Anvin
2004-07-30 19:39 ` Jim Paris
2004-07-30 19:45 ` H. Peter Anvin
2004-07-30 21:11 ` maarten van den Berg
2004-07-30 21:38 ` maarten van den Berg
2004-07-31 0:28 ` maarten van den Berg
2004-08-01 13:03 ` Kernel panic, FS corruption Was: " maarten van den Berg
2004-08-01 18:05 ` Jim Paris
2004-08-01 22:10 ` maarten van den Berg
2004-08-05 23:54 ` H. Peter Anvin
2004-08-06 0:19 ` Jim Paris
2004-08-06 0:36 ` H. Peter Anvin
2004-08-06 4:04 ` Jim Paris
2004-08-05 23:51 ` H. Peter Anvin [this message]
2004-08-05 23:46 ` H. Peter Anvin
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='ceuh5k$reo$1@terminus.zytor.com' \
--to=hpa@zytor.com \
--cc=linux-raid@vger.kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).