Messages in this thread | | | From | (bill davidsen) | Subject | Re: Software RAID5 with 2.6.0-test | Date | 21 Oct 2003 21:44:21 GMT |
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In article <20031017192419.GG8711@unthought.net>, Jakob Oestergaard <jakob@unthought.net> wrote:
| Now that I'm posting anyway - I thought of a plus for the HW RAID | controllers (hey, they're way behind on the scoreboard so far, so I | might as well be a gentleman and give them a point or two): | *) Battery backed write cache | | This will allow the controller to say 'ok I'm done with your sync()', | way before the data actually reaches the disk platters. For some | workloads this can be a big win.
Unless the drives are battery backed up as well, I'm not sure that this is a good thing, or at least a safe thing. And if a write error happens after the controller tells you the sync() is done? That's a question, not a comment, I'm not sure Linux software RAID would relocate if the drive was out of spare sectors, either, but it at least could.
I don't question your statement that caching helps performance, but I think there is some loss of reliability. I have no numbers to estimate the effect, so take it as a comment only. -- bill davidsen <davidsen@tmr.com> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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