Squid 2.7Stable7 F12 AUFS on a ext3 FS 6gigs ram dual proc cache_dir aufs /cache 32000 16 256 Filesystem Size Used Avail Use% Mounted on /dev/vda2 49G 3.8G 42G 9% /cache configure options: '--host=i686-pc-linux-gnu' '--build=i686-pc-linux-gnu' '--target=i386-redhat-linux' '--program-prefix=' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib' '--libexecdir=/usr/libexec' '--sharedstatedir=/var/lib' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--exec_prefix=/usr' '--libexecdir=/usr/lib/squid' '--localstatedir=/var' '--datadir=/usr/share/squid' '--sysconfdir=/etc/squid' '--with-logdir=$(localstatedir)/log/squid' '--with-pidfile=$(localstatedir)/run/squid.pid' '--disable-dependency-tracking' '--enable-arp-acl' '--enable-follow-x-forwarded-for' '--enable-auth=basic,digest,ntlm,negotiate' '--enable-basic-auth-helpers=LDAP,MSNT,NCSA,PAM,getpwnam,multi-domain-NTLM,SASL,squid_radius_auth' '--enable-ntlm-auth-helpers=no_check,fakeauth' '--enable-digest-auth-helpers=password,ldap' '--enable-negotiate-auth-helpers=squid_kerb_auth' '--enable-external-acl-helpers=ip_user,ldap_group,session,unix_group,wbinfo_group' '--enable-cache-digests' '--enable-cachemgr-hostname=localhost' '--enable-delay-pools' '--enable-epoll' '--enable-icap-client' '--enable-ident-lookups' '--with-large-files' '--enable-linux-netfilter' '--enable-referer-log' '--enable-removal-policies=heap,lru' '--enable-snmp' '--enable-ssl' '--enable-storeio=aufs,diskd,ufs' '--enable-useragent-log' '--enable-wccpv2' '--enable-esi' '--with-aio' '--with-default-user=squid' '--with-filedescriptors=16384' '--with-dl' '--with-openssl' '--with-pthreads' 'build_alias=i686-pc-linux-gnu' 'host_alias=i686-pc-linux-gnu' 'target_alias=i386-redhat-linux' 'CFLAGS=-fPIE -Os -g -pipe -fsigned-char -O2 -g -march=i386 -mtune=i686' 'LDFLAGS=-pie' No load to speak of, very little iowait. Threads were configured as the default. This is running on a striped pair of SSD's and is only a test script that (ya it's hitting it a bit hard), but nothing that squid nor my hardware should have an issue with. I've searched and really there does not appear to be a solid answer, except running out of cpu or running out of iops, neither "appears" to be the case here. Figured if it was a thread issue, I would see a bottleneck on my server? (ya?). Also the if it only happens a couple of times ignore it. This is just some testing and I believe this congestion is possibly causing the 500 errors I'm seeing while running my script. Any pointers, where to look etc? (2.7stable6 on fc6/xen kernel) had no such issues (yes, the SSD's are a new variable (but otherwise identical hardware). Thanks Tory avg-cpu: %user %nice %system %iowait %steal %idle 13.13 0.00 40.66 4.80 0.00 41.41 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn vda 1539.50 11516.00 6604.00 23032 13208 avg-cpu: %user %nice %system %iowait %steal %idle 13.60 0.00 38.29 11.08 0.00 37.03 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn vda 1385.07 11080.60 0.00 22272 0 [@cache01 ~]$ free total used free shared buffers cached Mem: 5039312 421768 4617544 0 50372 183900 -/+ buffers/cache: 187496 4851816 Swap: 7143416 0 7143416 Totals since cache startup: sample_time = 1266055655.813016 (Sat, 13 Feb 2010 10:07:35 GMT) client_http.requests = 810672 client_http.hits = 683067 client_http.errors = 0 client_http.kbytes_in = 171682 client_http.kbytes_out = 2145472 client_http.hit_kbytes_out = 1809060 server.all.requests = 127606 server.all.errors = 0 server.all.kbytes_in = 321960 server.all.kbytes_out = 38104 server.http.requests = 127606 server.http.errors = 0 server.http.kbytes_in = 321960 server.http.kbytes_out = 38104 server.ftp.requests = 0 server.ftp.errors = 0 server.ftp.kbytes_in = 0 server.ftp.kbytes_out = 0 server.other.requests = 0 server.other.errors = 0 server.other.kbytes_in = 0 server.other.kbytes_out = 0 icp.pkts_sent = 0 icp.pkts_recv = 0 icp.queries_sent = 0 icp.replies_sent = 0 icp.queries_recv = 0 icp.replies_recv = 0 icp.query_timeouts = 0 icp.replies_queued = 0 icp.kbytes_sent = 0 icp.kbytes_recv = 0 icp.q_kbytes_sent = 0 icp.r_kbytes_sent = 0 icp.q_kbytes_recv = 0 icp.r_kbytes_recv = 0 icp.times_used = 0 cd.times_used = 0 cd.msgs_sent = 0 cd.msgs_recv = 0 cd.memory = 0 cd.local_memory = 487 cd.kbytes_sent = 0 cd.kbytes_recv = 0 unlink.requests = 0 page_faults = 1 select_loops = 467112 cpu_time = 681.173445 wall_time = -40015.496720 swap.outs = 126078 swap.ins = 1366134 swap.files_cleaned = 0 aborted_requests = 0