On 6/30/2012 6:17 AM, Костырев Александр Алексеевич wrote:
So, you say that one should use this configuration in production with hope that such failure would never happen?
No, I'm saying you are trolling. A concat of RAID1 pairs has reliability identical to RAID10. I don't see you ripping a mirror pair from a RAID10 array and saying RAID10 sucks. Your argument has several flaws.
In a production environment, a dead drive will be replaced and rebuilt before the partner fails. In a production environment, the mirror pairs will be duplexed across two SAS/SATA controllers.
Duplexing the mirrors makes a concat/RAID1, and a properly configured RAID10, inherently more reliable than RAID5 or RAID6, which simply can't be protected against controller failure.
By stating the concat/RAID1 configuration is unreliable simply shows your ignorance of storage system design and operation.
-- Stan
-----Original Message----- From: dovecot-bounces@dovecot.org [mailto:dovecot-bounces@dovecot.org] On Behalf Of Stan Hoeppner Sent: Saturday, June 30, 2012 4:24 PM To: dovecot@dovecot.org Subject: Re: [Dovecot] RAID1+md concat+XFS as mailstorage
On 6/28/2012 7:15 AM, Ed W wrote:
On 28/06/2012 13:01, Костырев Александр Алексеевич wrote:
somewhere in maillist I've seen RAID1+md concat+XFS being promoted as mailstorage. Does anybody in here actually use this setup?
I've decided to give it a try, but ended up with not being able to recover any data off survived pairs from linear array when _the_first of raid1 pairs got down.
The failure of the RAID1 pair was due to an intentional breakage test. Your testing methodology was severely flawed. The result is the correct expected behavior of your test methodology. Proper testing will yield a different result.
One should not be surprised that something breaks when he intentionally attempts to break it.
This is the configuration endorsed by Stan Hoeppner.
Yes. It works very well for metadata heavy workloads, i.e. maildir.