Date: Mon, 24 Nov 2014 07:39:13 +0000 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: freebsd-questions@freebsd.org Subject: Re: How much space does raidz2 'eat'? Message-ID: <5472E0A1.7050007@infracaninophile.co.uk> In-Reply-To: <5472DB34.8080500@infracaninophile.co.uk> References: <20141123232623.39d46c80@falbala.rz1.convenimus.net> <5472DB34.8080500@infracaninophile.co.uk>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --5QBi5ddNhovnE28duRLT2qvotvQN9A8jI Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 24/11/2014 07:16, Matthew Seaman wrote: > On 23/11/2014 22:26, Christian Baer wrote: >> After creating a raidz2 pool, I get this: >=20 >> Now I know that while WD works with kB, FreeBSD works with KiB (factor= >> 1024). However, if I break this drive down to that and multiply that b= y >> 5, I get 18.19TiB, while df gives me 16TiB. Sure, there is some >> overhead and all, but certainly (hopefully) not 2 whole TiB! That woul= d >> be more than 10%. >=20 > Use 'zpool list' to see the actual size and usage of your pool. >=20 > The amount you lose in overhead from partitioning and setting up geli > providers is pretty neglible; it's all down (oops. missed a bit) =2E.. in the noise with the TB scale drives you're using. > Yes, RAIDZ2 has around that level of overhead: think two parity blocks > for each three data blocks, so worst case is that about 40% of your raw= > space will disappear. The actual amount depends on exactly how many > drives you're using. >=20 >> Is this normal or am I missing something? >=20 > See: http://blog.delphix.com/matt/2014/06/06/zfs-stripe-width/ >=20 > Cheers, >=20 > Matthew >=20 --=20 Dr Matthew J Seaman MA, D.Phil. PGP: http://www.infracaninophile.co.uk/pgpkey JID: matthew@infracaninophile.co.uk --5QBi5ddNhovnE28duRLT2qvotvQN9A8jI Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.20 (Darwin) iQJ8BAEBCgBmBQJUcuChXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXQ2NTNBNjhCOTEzQTRFNkNGM0UxRTEzMjZC QjIzQUY1MThFMUE0MDEzAAoJELsjr1GOGkATZDwP/A1wVhUk/sp1yg0agXXLAtEJ qyJr8QqJy8C/9l0TVbWz7Frd7ZeDp4FiTv9nwz5JsESRHd4yOP2wq3DdCYxfc1OR LSaHB7WJ0wzZbJ6xW9hLrjAWK0Y7es56rEcbe7dxp9+MTeW3CUk4F3D3a08d8f9O sHpjRqncx8zbckQxWzIO/2WVv8BM+DN73mgz5wDE+sZIymIhlIlsHu7ukrCz482k PIy8rUq70ZGg6CmZ6SVCfbsSOdPSzb8Rm3t8nE0AfeFdEzJjy4cWTOuTtudLxCZt zlZ1vuJFDA9wNQWJpFwG7QwJxKpHgMCK+zIfKAuyJJJzeGpBvhaWdT1gzy5T6guJ 82B9Y/coJmMYHr+rOaUNUZZzzQYNfMkPTx6zhohRj7VtKr09kW7nMamECE1W4R4E +sllZHPbbrRc94dxtqeds+yfpSavmu8bF/QTFsfzs6t5TVUgC6coVmpU6iN54v0J 4BTceSpQju3mFjQqdZR/n2gI41QlnSmAjseaBAm62kjRFmsZPjf/f9O0ZtCaynlv lUsTaHUDH09Yl4RU5UA3wzwVAUwl/9+wZijI4ifB/RryX4vvZOvHKluIcAekb88P 6RXb7rLR+PSjZVBHmEOzdRIyT1Lssk2HJNZRD6/jrTwYmHt/AqF8cC/S4YU7G51O VWsniA56nNSwoOqXlDDD =vkUJ -----END PGP SIGNATURE----- --5QBi5ddNhovnE28duRLT2qvotvQN9A8jI--
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