From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Thought about delayed sync Date: Mon, 10 Oct 2011 09:12:36 +1100 Message-ID: <20111010091236.5bcbacd8@notabene.brown> References: <20111008180309.GA14979@animx.eu.org> <20111009093641.4cfa79c9@notabene.brown> <20111009133216.Horde.3I8nXJk8pphOkYZAj4hRFEg@cakebox.homeunix.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/kwRQzKrcwcqeZwvOjUJy8xV"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20111009133216.Horde.3I8nXJk8pphOkYZAj4hRFEg@cakebox.homeunix.net> Sender: linux-raid-owner@vger.kernel.org To: Alexander =?ISO-8859-1?B?S/xobg==?= Cc: Wakko Warner , linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/kwRQzKrcwcqeZwvOjUJy8xV Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Sun, 09 Oct 2011 13:32:16 +0200 Alexander K=FChn wrote: >=20 > Zitat von NeilBrown : >=20 > > http://neil.brown.name/blog/20110216044002#5 >=20 > Using one bit per stripe looks like the natural choice to me, no? It might seem natural, but that doesn't mean it is good. My rule-of-thumb is that each bit should correspond to about one second of resync time. So that is probably 50-100MB these days. So a 4TB drive would have 40,000-80,000 bits or be 5KB to 10KB in size. I would probably rather a 4KB bitmap, so each bit could correspond to 2-3 seconds which is probably fine. That might line up with the stripe size, or it might not. And whether is does or not is largely irrelevant to the code. NeilBrown --Sig_/kwRQzKrcwcqeZwvOjUJy8xV Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBTpIcXTnsnt1WYoG5AQK6EA//UmC2wKaqpl0wKbE0rvuW7AASMosBTD9P 6E1s9bVusvPKhPZekR6A0lKzBHVAYIIYmxrVqMpW2cwE7zg7NARkpkaKq8IwiN3O ZQxSiczvh8urPrY+wMBCFvSbsI02XpY+cC8XeE+ZrGGr6YA4USi54RxSzjk6Yxl0 kKIFP8WDtzPDybYbxyxoe2RKg4RgAD4ks4bLCuYoElngFU17QFWJuWe0nw7puBOt JBT8v+ScsSzLGaQWnH2+rAzoMGvp909VQqVSo/HOa7VSPeQ0qLnCarxNwuyUH5tI JaKUPEDxxG6s/1UjcDQzqAq9mHcy0ZTp+NFWoHa8ulZ5bwZQjhiSG8/q5kfZOYik E/KPw/2wkNkx7jILO4VVsj1/mNK7fqtRXueqFad+ovABGqqMose/n5oV9s4yU6w4 /BD5GvFehnl7lsTh9377bf5B9NLIKvvjm4MIcCJAXBS+EoSDp1AK8+U6oMpUcwRt MNxyRCnTvcgtBOT4bFcTFzfLxI2FBKw+Q218sBJA/ZEDUxVkWREpM6Ah6nEcuSAF Zsaz/6teFJu8x0DhMypQQwn7a/4LsMemj3NxZFobGvO/u+kwIv0RSCmHYcvQRsii 7s+U3Wl44COShuEkb9l0fe7Axiyfi7fG0xcSfqggDvJKA2pp+aBxmTwvifgCWw6m iU74nlW55tg= =kXUO -----END PGP SIGNATURE----- --Sig_/kwRQzKrcwcqeZwvOjUJy8xV--