Date: Thu, 26 Mar 2015 15:54:58 -0700 From: Xin Li <delphij@delphij.net> To: Wojciech Puchar <wojtek@puchar.net>, freebsd-hackers@freebsd.org Subject: Re: Seagate Archive HDD Message-ID: <55148E42.80708@delphij.net> In-Reply-To: <alpine.BSF.2.20.1503261124380.1417@laptop.wojtek.intra> References: <alpine.BSF.2.20.1503261124380.1417@laptop.wojtek.intra>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 03/26/15 03:26, Wojciech Puchar wrote: > http://www.storagereview.com/seagate_archive_hdd_review_8tb > > i want to buy 2 such drives for backup server. > > This drives use shingled recording. > > Are anyone using them and can confirm they are compatible on > software level with other disks? I understand average random write > time would be 5-10 times slower than normal drive because of the > need of rewrite few full tracks worth of data, but otherwise will > then be compatible and can i use it as usual? My understanding is that the SMR drives are actually different class of storage device. The "drive managed" drives as shipped now tries to emulate normal hard drive's behavior but they present unique risks: for instance, a rewrite of a small block may end up in a read-modify-write of a much larger area, so we must refrain from doing such operations for critical file system data structure, probably by reorganizing the on-disk format to satisfy the need. That's said, if the backup is mostly something where you can group writes together and not being written often, the drives would be just fine working with today's OS and FS because the risk is not very big for that type of operation. If the backup is something "warm" (i.e. a replicated database that receives live update stream from a master one), or the power supply is not very reliable, it's a good idea to avoid these drives for now until we have SMR aware drivers and filesystems for the new type of disk (and I would expect the disk used with these be host managed ones, or we would probably need some quirks to tell the OS to avoid doing writes in bad way). Cheers, - -- Xin LI <delphij@delphij.net> https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.1.2 (FreeBSD) iQIcBAEBCgAGBQJVFI4/AAoJEJW2GBstM+nskW0P/jtbgja1GUZpBtqsqiYd4dQO EvmwY1Xvzk5tfQXTiYNH5GgEvNK3BoFz6GpYZgFPEgETA6v5WuuoKHnFQpFmf2Eq QK7QmwaQmon1NPzo9LAkCF21WIoq7ED/oRHk/djEHMNgwzhpdFNLno0YH20T0pG1 nQ+cJolZVD1ndtqRcKR1b9sRdnCFE+PRyr40DR9AsfXcOxUR7dKswzeaAs+Y/FTH UKvHSFWqzNcScATBrn5C/sATbWZblXai18HnoRB3j/S1v6uUonkzGu4aNsU+9Fg9 9hVnKvO75Z12UbxZZaOJZBJara8nZYgVDSQXK/o/Bm1bSEslT2sj4nqC3ZCOu8d8 HWj41qlnP2x6/FXei/kLxeX7KxunX2zKHtQeCGyiOQ5cAlXnE3BmkwBxz116hku2 i6SXT8+3wMHoqpSu0r8Z2es0+eoucP+WuHoHdzCHgPIZH5BGyoUALyH43ihLHV3u AixU6fTOvXz+BHiFXRGMFxlnThXkkbetHMtxWY/gaw8UMjrALLxQstV6CPXMTMpa 8vTe6WfBL5yEIeEL+ND5sFyaLwwkuoVNGjWyPxnNtU2S2p/wTvDiMEOz3wXJurDv VHf1Bz/dsDghEAeM9al4lJ8N3I3ubk0e7HmJxEac1GfQaNEfInCfOjmNfXKWk4Eb N3yEo3ChS7h9zsk73zOh =pImh -----END PGP SIGNATURE-----
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