Date: Mon, 18 May 2015 00:43:34 +0200 (CEST) From: Wojciech Puchar <wojtek@puchar.net> To: freebsd-hackers@freebsd.org Subject: Got seagate archive Was: Help with 8TB Seagate Archive Message-ID: <alpine.BSF.2.20.1505180034330.979@laptop.wojtek.intra> In-Reply-To: <alpine.BSF.2.20.1504120004410.1075@laptop.wojtek.intra> References: <alpine.BSF.2.20.1504120004410.1075@laptop.wojtek.intra>
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For others interested i have this drive running in backup server now. it's used with GEOM_ELI and UFS. What about performance: Excellent on reads. Tolerable on writes as long as you will not write more than 10-15GB in a short time, then it REALLY slows down. This "hardware managed" SMR drive puts all random writes in it's log which takes AFAIK 20GB of reserved space. When disk is idle or log is full, it performs real writes/rewrites to SMR chunks which is slow. >From my observation it do it in batches resulting in half a minute or so stalls. Stalls include reads. Overall write performance is tolerable still. Now i am in process of copying 3TB of data from other disk. Then it will be used as usual with running rsync once per day. Usually there are less than 20GB data transferred per day to one disk so it should consistently keep good performance. Overall i do recommend this drive to any use that does not require heavy random write I/O including: - backup server - read-mostly data storage. - very large file storage, with properly tuned filesystem (64kB blocks, maybe even more after modifying kernel). Finally, contrary to what i read, it is not 4KB native, but 4K emulated. smartctl reports 4KB physical and 512B logical sectors. Of course make sure you use 4kB alignment, 4kB GELI blocks, and at least 4kB UFS fragments. it's really cheap for it's size, silent and low power. But it would be nicer if stalls on log full would not include reads. No opinion for ZFS users, i don't use, nor plan to use ZFS anywhere.
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