Date: Sat, 21 Jan 2017 12:47:04 +0300 From: Alex Povolotsky <tarkhil@webmail.sub.ru> To: "D. E" <cipher_nl@hotmail.com>, "fs@freebsd.org" <fs@freebsd.org> Subject: Re: Poor ZFS performance Message-ID: <e30bf385-8e5e-d274-35f5-778f380b1277@webmail.sub.ru> In-Reply-To: <DB6PR0801MB1622E364F7E7BBA170ADCE6397700@DB6PR0801MB1622.eurprd08.prod.outlook.com> References: <083391de-d153-e0f6-c453-63d95d3e1f55@webmail.sub.ru> <DB6PR0801MB1622E364F7E7BBA170ADCE6397700@DB6PR0801MB1622.eurprd08.prod.outlook.com>
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So fetching data to, say, ST2000NM0055-1V4104, and than zfs send | zfs receive to Archive HDD will do the trick? Seems like the answer is "yes", I've got 3-4 times speed improvement. In an hour, I'll try partial transfer. What 8 Tb disk would you recommend for raidz? On 21.01.2017 12:26, D. E wrote: >> I'm writing lots of (tens of millions) relatively small files, hashing >> them out in three-level directory, 100 entries per level. > >> Speed is quite unsatisfying, about 2 millions files per day writing in >> 20 processes, that is, about one file per second for process. > > But that is to be expected, isn't it? You have chosen hardware which is *EXTREMELY* slow for non-contiguous write access. The Seagate Archive HDD is an SMR harddrive suitable for archive storage - not a generic PMR harddrive. So the Seagate Archive HDD is suitable for makings backups and writing huge files like 1TB images which you write from A to Z. SMR drives are notoriously slow when it comes to non-contiguous writes, such as writing small files. > > You can read warnings about SMR and the Seagate Archive HDD in particular everywhere on the web. Have you missed them? > > Slightly exaggerated: your SMR-drive is more like a tapestreamer than a real harddrive. It should be used to store enormous files and used for 'cold storage'. > > Read more about the Seagate Archive HDD on its website: http://www.seagate.com/enterprise-storage/hard-disk-drives/archive-hdd/ > > To be honest, it is the worst harddrive one can buy today for the purpose of regular storage (hot storage). For cold storage, such as backups like tapestreamers do the drive is decent, but not good by any means. 1,33TB per platter is disappointing for SMR considering the massive downsides. And some PMR drives are even cheaper per gigabyte than this SMR drive. So i strongly recommend against SMR at this time. > > Regards, > CiPHER >
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