[lustre-discuss] No read_cache on OSS

[Thomas Roth]

Hi all,

have to come back to this bothering issue with the vanished osd-zfs read_cache paramters.

This is Lustre 2.10.6 with ZFS 0.7.9-1 on CentOS 7.5.1804


Consistently on all OSS, the cache paramters are dead links:

ls -l /proc/fs/lustre/obdfilter/*/

lrwxrwxrwx  1 root root 48 Jan 22 11:49 read_cache_enable -> ../../osd-zfs/*/read_cache_enable
lrwxrwxrwx  1 root root 53 Jan 22 11:49 readcache_max_filesize -> ../../osd-zfs/*/readcache_max_filesize

lrwxrwxrwx  1 root root 56 Jan 22 11:49 writethrough_cache_enable -> 
../../osd-zfs/*/writethrough_cache_enable




ls -l /proc/fs/lustre/osd-zfs/*/

-r--r--r-- 1 root root 0 Jan 22 11:51 blocksize
-rw-r--r-- 1 root root 0 Jan 22 11:51 brw_stats
-r--r--r-- 1 root root 0 Jan 22 11:51 filesfree
-r--r--r-- 1 root root 0 Jan 22 11:51 filestotal
--w------- 1 root root 0 Jan 22 11:51 force_sync
-r--r--r-- 1 root root 0 Jan 22 11:51 fstype
-r--r--r-- 1 root root 0 Jan 22 11:51 kbytesavail
-r--r--r-- 1 root root 0 Jan 22 11:51 kbytesfree
-r--r--r-- 1 root root 0 Jan 22 11:51 kbytestotal
-r--r--r-- 1 root root 0 Jan 22 11:51 mntdev
dr-xr-xr-x 2 root root 0 Jan 22 11:51 quota_slave
-rw-r--r-- 1 root root 0 Jan 22 11:51 stats



The Lustre Manual and all Google hits still talk about setting or switching off the read_cache, 
speculating about the best size for max_filesize, but nowhere is there an indication that these 
parameters are deprecated and disappearing.

Given that our users start clamouring for anything but Lustre due to the abysmal read performance, the 
possible misconfiguration here is a rather pressing matter.

Any ideas?


Regards,
Thomas




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Thomas Roth
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