Re: Postgres slave not catching up (on 9.2)

Indeed I could save some IO with noatime. I must say I haven’t found any recommendation about mount options for postgresql, likely because this is not encourage. The ones you see are taking from a Oracle cluster configuration where several nodes see the same files. It's not the case on this setup.

The IO is not an issue. The storage is not at all saturated. Slave gets streaming perfectly but the apply is quite slow, looks like always working with pages of 8k at a time:

--datafiles
[root@ ~]# /ORA/dbs01/syscontrol/projects/dfm/bin/smetrics -i 5 -n 100 -o vol dbnasg403-12a:/vol/dodpupdbtst03 Instance total_ops read_ops write_ops read_data write_data avg_latency read_latency write_latenc
/s /s /s b/s b/s us us us
dodpupdbtst03 6466 0 162 0 2350619 31.53 0 764.70
dodpupdbtst03 6762 0 843 0 8751169 48.32 0 263.10
dodpupdbtst03 7023 0 1547 0 14914498 112.88 0 303.16
dodpupdbtst03 5373 0 321 6501 3809930 58.44 11287.75 467.21
dodpupdbtst03 5618 0 183 0 1661200 20.91 0 265.61
dodpupdbtst03 5538 0 214 0 3471380 29.24 0 374.27
dodpupdbtst03 5753 0 425 0 4973131 45.36 0 351.08
dodpupdbtst03 6110 0 142 0 2331695 20.96 0 378.95

--WALs
Bye Bye[root@ ~]# /ORA/dbs01/syscontrol/projects/dfm/bin/smetrics -i 5 -n 100 -o vol dbnasg401-12a:/vol/dodpupdbtst02 Instance total_ops read_ops write_ops read_data write_data avg_latency read_latency write_latenc
/s /s /s b/s b/s us us us
dodpupdbtst02 1017 202 93 5915899 2637111 2033.22 10116.09 172.61
dodpupdbtst02 1284 242 141 7368712 4309409 1235.11 6306.37 172.89
dodpupdbtst02 1357 231 268 6869816 8489466 957.55 5104.09 192.26
dodpupdbtst02 1566 264 288 8142965 9008529 747.96 4069.78 180.00
dodpupdbtst02 1333 235 153 7601051 4755791 993.81 5394.99 176.99
dodpupdbtst02 1261 199 287 6124821 9075170 896.32 5150.28 203.81
dodpupdbtst02 963 161 192 4955996 6066333 1757.66 10035.06 213.12
dodpupdbtst02 924 159 157 4782617 4807262 1092.61 5804.85 236.91
dodpupdbtst02 591 97 137 2899085 4275046 1218.24 6980.66 190.20

Writes are usually fast (us as they use the NVRAM )and reads are about 5 ms which is quite ok considering SATA disks (they have a flash cache of 512GB, this is why we get this average).

Thank you,
Ruben