From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: RAID10 Write Performance Date: Wed, 23 Dec 2015 13:20:49 +1100 Message-ID: <87wps529dq.fsf@notabene.neil.brown.name> References: Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Marc Smith , linux-raid@vger.kernel.org List-Id: linux-raid.ids --=-=-= Content-Type: text/plain On Wed, Dec 23 2015, Marc Smith wrote: > Solved... appears it was the write-intent bitmap that caused the > performance issues. I discovered if I left the test running longer > than 60 seconds, the performance would eventually climb to where I'd > expect it. I ran 'mdadm --grow --bitmap=none /dev/md0' and now random > write performance is high/good/stable right off the bat. Keeping a write-intent bitmap really is a good idea. Using a larger bitmap chunk size can reduce the performance penalty and preserve much of the value. It is easy enough to experiment with different sizes. NeilBrown --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJWegUBAAoJEDnsnt1WYoG5GCQP/1fG7hTXO1HH6DQ8VZf4ydyA f2NcgdQk3d4WE4JTME5r20OddwJc5Vk/a49F5Muw3+0my0JNtQWNO/LrNLpIkmKZ Q9xo6meazaPM09emlLBIamjIZOMqRr5Uy/n8rbECz4mLTSOX77Js04ZLwSomicMl LuD/j60d2ncx6S5UZO8Q+1QGy+SpPcEKSxxKJmNTFWqe5VI0ROJkFMRkO6pKDWph Xo5FMNVN8iLRzbZs0uyEbFyRuAkMCl05j4JTAmeYp87/rKXQqWJxE7mPipux18LD +sVNsVOptsilQZQp6Ykh4Amry+o2mIKdZ8FE6ySuTTN91CTDy0YOMi2gQoIxoAGE jnT+xEHbNFyH+Kv7y2rKGqDtUpfad4OVg2KLeWBTHDvUFnGlZRIeyJoDzipYHJz3 l4XiQ1pAIuSsq+lCrf+mHYJT9nRbFQql0t/KafsIFbs864W1HezPKbjgYE2qQIJW 4TBKXNR7D2bvGQpF8hk9bIfdjEs7bs1aiD/+mOhGOSO96zLH++L2aHdC2AFvSonw ojPdw2kP9zW85am6Nc9j7KKDuDQmMveGETwb1iQWETJ82HPivl0APUi2CAr8PGwI EfthU7KyIzPDzn+qK4hvm2xFwTouHPSM+3Z/BF7hhZ348jQkkDdnPYQSuALsTX3g qetkLWsenYOAozHhMway =q9B0 -----END PGP SIGNATURE----- --=-=-=--