Date: Mon, 13 Feb 2012 17:51:35 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: Odd RAID Performance Issue Message-ID: <jhbf2o$7f6$1@dough.gmane.org> In-Reply-To: <4F3922A8.2090808@softhammer.net> References: <4F3922A8.2090808@softhammer.net>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig30C27DE334A3890B8C08E44E Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 13/02/2012 15:48, Stephen Sanders wrote: > We've an application that logs data on one very large raid6 array > and updates/accesses a database on another smaller raid5 array. You would be better off with RAID10 for a database (or anything which does random IO). > Both arrays are connected to the same PCIe 3ware RAID controller. The= > system has 2 six core 3Ghz processors and 24 GB of RAM. The system is > running FreeBSD 8.1. Did you do any additional OS tuning? Do you use UFS or ZFS? > The problem we're encountering is that the disk subsystem appears to > 'pause' periodically. It looks as if this is a result of disk read/wr= ite > operations from the database array taking a very long time to complete > (up to 8 sec). You should be able to monitor this with "iostat -x 1" (or whatever number of seconds instead of "1") - the last three columns should tell you if the device(s) are extraordinarily busy, and the r/s and w/s columns should tell you what the real IOPS rate is. You should probably post a sample output from this command when the problem appears. --------------enig30C27DE334A3890B8C08E44E Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk85P5cACgkQldnAQVacBcjySgCfSpFYYZBfvTXUmAaC3ONDpAmO aVcAn3cTAUGdYVRiFIOm8l6lFSvU6eQ2 =xvj2 -----END PGP SIGNATURE----- --------------enig30C27DE334A3890B8C08E44E--
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