From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Mamedov Subject: Re: btrfs on ssd and hdd Date: Sat, 14 Jan 2012 21:18:45 +0600 Message-ID: <20120114211845.38888a94@natsu> References: <1289964295.1201326553279203.JavaMail.root@shiva> <772574965.1221326553343545.JavaMail.root@shiva> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/v2hSt5rn.qFzO12JiSWY9wh"; protocol="application/pgp-signature" Cc: linux-btrfs@vger.kernel.org To: luvar@plaintext.sk Return-path: In-Reply-To: <772574965.1221326553343545.JavaMail.root@shiva> List-ID: --Sig_/v2hSt5rn.qFzO12JiSWY9wh Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sat, 14 Jan 2012 16:02:23 +0100 (GMT+01:00) luvar@plaintext.sk wrote: > I am using for my workspace btrfs filesystem on ssd disk. I do not thrust= to my ssd and I want to have backup of all data on rotational hdd (raid5 o= f 5 disks). If I am not wrong, this can be done when I use btrfs on top of = two phycical media (one ssd and second md device). This I think would work = fine. >=20 > My question is, does btrfs recognize poor latency of md device and will p= reform most reads from ssd? (I want to set raid1 for metadata and also to d= ata). (side question, should be ssd in parameters of mount?) >=20 > PS: Is this crazy idea, or normal (planned) usecase? Hello, This is not a crazy idea, and it's already possible in MD-based RAID. Run 'man md' and 'man mdadm' and do a search for 'write-mostly' to read mor= e about it. However I don't think the same feature has been implemented in BTRFS yet. --=20 With respect, Roman ~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Stallman had a printer, with code he could not see. So he began to tinker, and set the software free." --Sig_/v2hSt5rn.qFzO12JiSWY9wh Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk8RnNUACgkQTLKSvz+PZwiGOgCfR6xH9qjR7IecR3E/33E/Lbh0 aVkAni6vx1iNfk5bpIK84b6o8kmaKnYx =lkrp -----END PGP SIGNATURE----- --Sig_/v2hSt5rn.qFzO12JiSWY9wh--