From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tobias Subject: Re: Extreme slowdown Date: Fri, 16 Dec 2011 10:09:14 +0100 Message-ID: <4EEB0ABA.5050202@robotech.de> References: <4EEA4124.20907@robotech.de> <4EEAC5D7.80707@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: Chester , "Fajar A. Nugraha" , Linux Btrfs To: nspmangalore@gmail.com Return-path: In-Reply-To: <4EEAC5D7.80707@gmail.com> List-ID: Am 16.12.2011 05:15, schrieb Shyam Prasad N: > On 12/16/2011 09:14 AM, Chester wrote: >> On Thu, Dec 15, 2011 at 8:19 PM, Fajar A. Nugraha >> wrote: >>> On Fri, Dec 16, 2011 at 1:49 AM, Tobias wrote: >>>> Hi all! >>>> >>>> My BTRFS-FS ist getting really slow. Reading is ok, writing is slow >>>> and >>>> deleting is horrible slow. >>>> >>>> There are many files and many links on the FS. >>>> >>>> # btrfs filesystem df /srv/storage >>>> Data: total=3.09TB, used=3.07TB >>> this is ... what, over 99% full? >>> The slow down is normal, somewhat. Same thing happens on zfs, which >>> became slower when usage is above 80-90%. >> I don't think "total" actually means "total space available" it >> increases as you use up more space. Chester is right, the disk is a 8TB Array - the fs is less than half filled. > Wouldn't it be more valuable to first collect enough info/data to > debug the problem, before suggesting ways to get out of this situation? > > AFAIK, the slowness could be due to several reasons: > 1. Slow disk writes. That depends on what is slow for you. Its a SATA-Disc-Array so good linear Read/Write and low IOPs (compared to SSDs or SAS-Discs) > 2. Too many things to commit to the disk. I think there should be very little data to write/commit when deleting files. Remember: writing is slow, but acceptable - deleting is the problem > 3. Too many things to do to actually accomplish the writes. I just do rm -rf xxx. What has BTRFS to do to actually delete a file or directory? > Is there some sort of profiling which we can enable, which can give us > info about the speeds and quantities of read and write traffic on the fs? > Aren't there btrfs statistics that we can print out, which can give us > these info? If not, we probably should think about adding some. Good question - maybe a dev can say? Tobias