Nothing special, just: standby_mode = 'on' primary_conninfo = 'host=... user=repmgr application_name=nodex' recovery_target_timeline = 'latest'
Boris On Tue, Oct 23, 2018 at 3:10 PM, Hellmuth Vargas <hiv...@gmail.com> wrote: > Hi > > can share recovery.conf file settings?? > > El mar., 23 de oct. de 2018 a la(s) 00:28, Boris Sagadin ( > bo...@infosplet.com) escribió: > >> Yes, turning wal_compression off improves things. Slave that was >> mentioned unfortunately lagged too much before this setting was applied and >> was turned off. However the remaining slave lags less now, although still >> occasionally up to a few minutes. I think single threadedness of recovery >> is a big slowdown for write heavy databases. Maybe an option to increase >> wal_size beyond 16MB in v11 will help. >> >> In the meantime we'll solve this by splitting the DB to 2 or 3 clusters >> or maybe trying out some sharding solution like Citus. >> >> >> Boris >> >> On Sun, Oct 21, 2018 at 9:06 AM, Boris Sagadin <bo...@infosplet.com> >> wrote: >> >>> Hello, >>> >>> I have a database running on i3.8xlarge (256GB RAM, 32 CPU cores, 4x >>> 1.9TB NVMe drive) AWS instance with about 5TB of disk space occupied, ext4, >>> Ubuntu 16.04. >>> >>> Multi-tenant DB with about 40000 tables, insert heavy. >>> >>> I started a new slave with identical HW specs, SR. DB started syncing >>> from master, which took about 4 hours, then it started applying the WALs. >>> However, it seems it can't catch up. Delay is still around 3 hours >>> (measured with now() - pg_last_xact_replay_timestamp()), even a day >>> later. It goes a few 100s up and down, but it seems to float around 3h mark. >>> >>> Disk IO is low at about 10%, measured with iostat, no connected clients, >>> recovery process is at around 90% CPU single core usage. >>> >>> Tried tuning the various parameters, but with no avail. Only thing I >>> found suspicious is stracing the recovery process constantly produces many >>> errors such as: >>> >>> lseek(428, 0, SEEK_END) = 780124160 >>> lseek(30, 0, SEEK_END) = 212992 >>> read(9, 0x7ffe4001f557, 1) = -1 EAGAIN (Resource >>> temporarily unavailable) >>> lseek(680, 0, SEEK_END) = 493117440 >>> read(9, 0x7ffe4001f557, 1) = -1 EAGAIN (Resource >>> temporarily unavailable) >>> lseek(774, 0, SEEK_END) = 583368704 >>> >>> ...[snip]... >>> >>> read(9, 0x7ffe4001f557, 1) = -1 EAGAIN (Resource >>> temporarily unavailable) >>> lseek(774, 0, SEEK_END) = 583368704 >>> read(9, 0x7ffe4001f557, 1) = -1 EAGAIN (Resource >>> temporarily unavailable) >>> lseek(277, 0, SEEK_END) = 502882304 >>> lseek(6, 516096, SEEK_SET) = 516096 >>> read(6, >>> "\227\320\5\0\1\0\0\0\0\340\7\246\26\274\0\0\315\0\0\0\0\0\0\0}\0178\5&/\260\r"..., >>> 8192) = 8192 >>> read(9, 0x7ffe4001f557, 1) = -1 EAGAIN (Resource >>> temporarily unavailable) >>> lseek(735, 0, SEEK_END) = 272809984 >>> read(9, 0x7ffe4001f557, 1) = -1 EAGAIN (Resource >>> temporarily unavailable) >>> lseek(277, 0, SEEK_END) = 502882304 >>> >>> ls -l fd/9 >>> lr-x------ 1 postgres postgres 64 Oct 21 06:21 fd/9 -> pipe:[46358] >>> >>> >>> Perf top on recovery produces: >>> >>> 27.76% postgres [.] pglz_decompress >>> 9.90% [kernel] [k] entry_SYSCALL_64_after_swapgs >>> 7.09% postgres [.] hash_search_with_hash_value >>> 4.26% libpthread-2.23.so [.] llseek >>> 3.64% libpthread-2.23.so [.] __read_nocancel >>> 2.80% [kernel] [k] __fget_light >>> 2.67% postgres [.] 0x000000000034d3ba >>> 1.85% [kernel] [k] ext4_llseek >>> 1.84% postgres [.] pg_comp_crc32c_sse42 >>> 1.44% postgres [.] hash_any >>> 1.35% postgres [.] 0x000000000036afad >>> 1.29% postgres [.] MarkBufferDirty >>> 1.21% postgres [.] XLogReadRecord >>> [...] >>> >>> Tried changing the process limits with prlimit to unlimited, but no >>> change. >>> >>> I can turn off the WAL compression but I doubt this is the main culprit. >>> Any ideas appreciated. >>> >>> Regards, >>> Boris >>> >>> >> > > -- > Cordialmente, > > Ing. Hellmuth I. Vargas S. > Esp. Telemática y Negocios por Internet > Oracle Database 10g Administrator Certified Associate > EnterpriseDB Certified PostgreSQL 9.3 Associate > >
