Date: Mon, 21 Jan 2019 12:35:24 +0000 From: Steve O'Hara-Smith <steve@sohara.org> To: Yasuhiro KIMURA <yasu@utahime.org> Cc: freebsd-questions@freebsd.org Subject: Re: Performance degradation of ZFS? Message-ID: <20190121123524.3c97bdfb2254e3393a58b831@sohara.org> In-Reply-To: <20190121.210941.2275299827563542964.yasu@utahime.org> References: <20190121.210941.2275299827563542964.yasu@utahime.org>
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On Mon, 21 Jan 2019 21:09:41 +0900 (JST) Yasuhiro KIMURA <yasu@utahime.org> wrote: > Is it possible that I/O performance degrade while using ZFS for a long > time? And if answer is yes is there any way to recover performance > without making full backup and restore? How is the pool configured ? How full is it ? How well is the data striped (are some vdevs fuller than others) ? Are any of the drives showing trouble ? Do you run a regular scrub ? What does zpool status show ? I can think of several ways in which ZFS performance can become degraded (and there are probably a good many I haven't thought of) but time passing is not enough alone, something has to be going astray. Those questions should help pin down what. What it will take to recover depends greatly on the cause, you may find (for example) that replacing a flaky drive (not failing just making too many retries) will bring dramatic improvement or you might be unlucky and have developed hideously imbalanced stripes for which there is no cure but to wipe and rebuild. -- Steve O'Hara-Smith <steve@sohara.org>
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