Article ID: 126068, created on Jul 2, 2015, last review on Jun 17, 2016

  • Applies to:
  • Virtuozzo 6.0

Question

What are the recommendations for configuring CS journals and client cache

Answer

advise-configuration tool should help to choose the best SSD configuration, e.g.:

# pstorage -c pstorage1 advise-configuration --cs /hdd1 --cs /hdd2 --cs /hdd3 --ssd /ssd -m /mnt/pstorage
You have the following setup:
CS on /hdd3 -- Total disk space 125.9GB
CS on /hdd2 -- Total disk space 125.9GB
CS on /hdd1 -- Total disk space 97.2GB
SSD on /ssd -- Total disk space 12.4GB
Proposed server configuration
- 5.4GB (43%) for CS journals, 5.4GB (43%) for mount read cache,
1.5GB (12%) reserved (including 349MB checksums for 349.2GB of data)
- CS journal sizes:
1.9GB for /hdd3
1.9GB for /hdd2
1.5GB for /hdd1
How to setup the node:
pstorage -c pcs1 make-cs -r /hdd3 -j /ssd/cs3-pcs1-journal -s 2015
pstorage -c pcs1 make-cs -r /hdd2 -j /ssd/cs2-pcs1-journal -s 2015
pstorage -c pcs1 make-cs -r /hdd1 -j /ssd/cs1-pcs1-journal -s 1555
pstorage-mount -c pcs1 /mnt/pstorage -C /ssd/pstorage-pcs1-cache -R 5585
Mount option for automatic cluster mount from /etc/fstab:
pcs1 /mnt/pstorage fuse.pstorage cache=/ssd/pstorage-pcs1-cache,cachesize=5585

in the example above all mount points for regular HDD were passed with --cs option, all mount points for SSD drives were passed with --ssd option, cluster storage mount point was passed with -m option.

advise-configuration tool splits SSD drives equally between journals and client caches, resulting scheme should be close to the following:

  • 20 % reserved for checksums and emergency needs and also to prevent the SSD from filling up completely (because its performance would then degrade),
  • 40 % for read cache,
  • 40 % for write journals,

Such configuration is considered to be suitable for most cases, however, it is possible to map SSD with priority of journals space or client caches if a node holds more than average number of CSs or VEs.

See Also

Search Words

ssd storage

advise-configuration

best practices

ssd

c62e8726973f80975db0531f1ed5c6a2 2897d76d56d2010f4e3a28f864d69223 0dd5b9380c7d4884d77587f3eb0fa8ef

Email subscription for changes to this article
Save as PDF