Date: Thu, 23 Aug 2012 11:31:15 +0200 From: Fabian Keil <freebsd-listen@fabiankeil.de> To: freebsd-fs@freebsd.org Subject: Re: `zpool create' fails on geli ... Message-ID: <20120823113115.298aca04@fabiankeil.de> In-Reply-To: <201208221728.04712.Mark.Martinec%2Bfreebsd@ijs.si> References: <20120821190742.54449@relay.ibs.dn.ua> <20120822123535.0385f118@fabiankeil.de> <20120822132905.GA53612@wonko.batmule.dk> <201208221728.04712.Mark.Martinec%2Bfreebsd@ijs.si>
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--Sig_/L1r0EPUC5yk2msGK7lFwwLx Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Mark Martinec <Mark.Martinec+freebsd@ijs.si> wrote: > > Fabian Keil wrote: > > > Zeus Panchenko <zeus@ibs.dn.ua> wrote: > > > > geli init -K /path/key -s 4096 -e aes-xts /dev/adaX > > >=20 > > > Does your disk actually use 4k sectors? Otherwise it's not clear > > > to me that "-s 4096" makes sense when using ZFS. > > >=20 > > > I'm not claiming that it's obviously wrong, but I'm not aware of > > > any benchmarks that show that it's better than the default in > > > any way. I probably should have clarified that I don't deny that workloads exist where using 4k sectors indeed improves the performance even if the disk is using smaller sectors. > It benefits geli performance (tried it, it does): You probably didn't test with random read or write operations of less than 4k, for which a smaller sector size should result in better performance. > $ man geli > -s sectorsize Change decrypted provider's sector size. > Increasing sector size allows to increase per- > formance, because we need to generate an IV > and do encrypt/decrypt for every single sector > - less number of sectors means less work to Provided you actually need the content of the whole sector ... And if you always do, why not increase the sector size even further? If -s 4096 would provide the best results for all work loads it probably would be the default already. > > It is my understanding that creating a 4K setup will prepare you > > for the day when your replacement drive is a 4K one. That's true and I didn't consider this (I don't usually replace drives in single-drive pools). > > No benefit today, but also no real performance hit. And we avoid > > a real performance hit later. =20 As I said previously, I'm not aware of any benchmarks that show how much impact the geli sector size has on the ZFS performance. Fabian --Sig_/L1r0EPUC5yk2msGK7lFwwLx Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iEYEARECAAYFAlA1+GcACgkQBYqIVf93VJ2H4gCbBZzL+s0Ez5Bm/zXdZADPxaPl DBMAn1Zv9jqpaGq3GIGFBZJopufKJ6jM =5LU6 -----END PGP SIGNATURE----- --Sig_/L1r0EPUC5yk2msGK7lFwwLx--
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