Thursday 28 August 2008 15:29:06 Łukasz Mierzwa napisał(a): > Thursday 28 of August 2008 12:39:03 napisałeś(-łaś): > > On Thu, Aug 28, 2008 at 3:01 PM, Łukasz Mierzwa <l.mierzwa@xxxxxxxxx> wrote: > > > Thursday 28 of August 2008 07:06:30 Krishna Srinivas napisał(a): > > >> On Wed, Aug 27, 2008 at 10:55 PM, Łukasz Mierzwa <l.mierzwa@xxxxxxxxx> > > > > > > wrote: > > >> > Tuesday 26 August 2008 16:28:41 Łukasz Mierzwa napisał(a): > > >> >> Hi, > > >> >> > > >> >> I testing glusterfs for small files storage, first I've setup a > > >> >> single disk gluster server, connected to it from another machine > > >> >> and served those files with nginx. That worked ok, I got good > > >> >> performance, on average about +20ms slower for each request but > > >> >> that's ok. Now I've setup unify over afr (2 afr groups with 3 > > >> >> servers each, unify and afr on the client side, namespace dir is on > > >> >> every server, as other stuff afr'ed on the client side), this is > > >> >> mounted on one of those 6 servers. After writing ~200GB files from > > >> >> production server I started to do some tests and I've noticed that > > >> >> doing simple ls on that mount point causes as many writes as reads, > > >> >> this has to do something to either unify or afr, I suspect that > > >> >> those writes are do to namespace but I need to do more debugging. > > >> >> It's very annoying that simple reads are causing so many writes. > > >> >> All my servers are in sync so there should not be any need for > > >> >> sealf-healing. Before I start debugging it I wanted to ask if this > > >> >> is normal? Shoud afr or unify generate so many writes to namespace > > >> >> or maybe xattrs during reads (storage is on ext3 with users_xattrs > > >> >> on)? > > >> > > > >> > I tested it a little bit today and I found out that if I got 1 or 2 > > >> > nodes in my afr group for namespace there are no writes at all while > > >> > doing ls, if I add one or more nodes they are starting to get > > >> > writes. WTF? > > >> > > >> Do you mean that your NS is getting write() calls when you do "ls"? > > > > > > It seems so. I will split my NS and DATA bricks to different disks > > > today so I will be 100% sure. What I am sure now is that I am getting > > > as many writes as reads when I do "ls" and have more than 2 NS bricks > > > in AFR. > > > > reads/writes should not happen when you do an 'ls' where are you seeing > > reads and writes being done? How are you seeing it? are you strace'ing > > the glusterfsd? > > > > Krishna > > I first noticed them when I looked at rrd graphs for those machines, I > wanted to see if AFR is balancing reads. I can see them in rrd graphs > generated from collectd, dstat, iotop and iostat, they are happening. I > first tried to find something in my config and forgot about such obvious > step as straceing glusterfs. I attach log from one of the servers, I > straced gluster-server on this machine, You can see that there is a lot of > mkdir/chown/chmod on files that are already there, all bricks were online > when I was writing files to gluster client so no self-heal should be > needed. I've also attached client and server configs. I attached strace log from gluster-server, this time I removed all but last two ns servers, I straced brick with ns, no mkdir/chmod this time. -- Łukasz Mierzwa Grono.net S.A. ul. Szturmowa 2a, 02-678 Warszawa Sąd Rejonowy dla m.st. Warszawy, XIII Wydział Gospodarczy; Nr KRS 0000292169 , NIP: 929-173-90-15 Regon: 141197097 Kapitał zakładowy: 550.000,00 zł http://grono.net/ Treść tej wiadomości jest poufna i prawnie chroniona. Odbiorca może być jedynie jej adresat z wyłączeniem dostępu osób trzecich. Jeżeli nie jesteś adresatem niniejszej wiadomości, jej rozpowszechnianie, kopiowanie, rozprowadzanie lub inne działanie o podobnym charakterze jest prawnie zabronione i może by karalne. Jeżeli wiadomość ta trafiła do Ciebie omyłkowo, uprzejmie prosimy o odesłanie jej na adres nadawcy i usunięcie.
