Date: Fri, 31 Jan 2003 16:01:13 -0500 From: Steve Byan <stephen_byan@maxtor.com> To: David Schultz <dschultz@uclink.Berkeley.EDU> Cc: phk@FreeBSD.ORG, freebsd-fs@FreeBSD.ORG, tech-kern@netbsd.org Subject: Re: DEV_B_SIZE Message-ID: <21B8D16C-355F-11D7-B26B-00306548867E@maxtor.com> In-Reply-To: <20030131192452.GA15985@HAL9000.homeunix.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Friday, January 31, 2003, at 02:24 PM, David Schultz wrote: > If the disk corrupts a sector it was writing, that's already a > problem for us. From the Maxtor Atlas 10K III Product Spec: Section 4.5.1 Power Sequencing You may apply the power in any order or manner, or open either the power or power return line with no loss of data or damage to the disk drive. However, data may be lost in the sector being written at the time of power loss. The drive can withstand transient voltages of +10% to –100% from nominal while powering up or down. > If the sector is 4K, that just makes it more of a > problem. With FFS and soft updates, we assume that the disk can > atomically write 512 bytes, and we ensure filesystem consistency > by establishing a safe partial ordering for metadata updates. We > expect that after a crash, either the old contents or the new > contents of the sector are there. I think we would need to > implement journalling to ensure integrity if hard drives were > likely to corrupt sectors on power failure. (How often do they do > this right now, and how often would they with 4K sectors?) If you are doing nothing but continuously writing, the active data area covers more than 50% of the track, so you'd have more than a 0.5 probability of experiencing a corrupt sector. Derate this by your seek duty-cycle and your write disk utilization to arrive at the final probability. Regards, -Steve -------- Steve Byan <stephen_byan@maxtor.com> Design Engineer Maxtor Corp. MS 1-3/E23 333 South Street Shrewsbury, MA 01545 (508) 770-3414 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?21B8D16C-355F-11D7-B26B-00306548867E>