Squid/キャッシュストレージとして COSS を使う - maruko2 Note.
上記ページにも記載されているようにsquidはページキャッシュを1オブジェクト(1ページとイコール？)1ファイルで保持するらしいのだが、ディスクI/Oの負荷が高いため1ファイルでまとめて管理可能なCOSSタイプに変更してみます。
とはいっても、上記ページに書いてある事をそのままやっただけで、かつ体感で早くなったとかはなく気分の問題って気もする。
# TAG: cache_dir
# Usage:
#
# cache_dir Type Directory-Name Fs-specific-data [options]
#
# You can specify multiple cache_dir lines to spread the
# cache among different disk partitions.
#
# Type specifies the kind of storage system to use. Only "ufs"
# is built by default. To enable any of the other storage systems
# see the --enable-storeio configure option.
#
# 'Directory' is a top-level directory where cache swap
# files will be stored. If you want to use an entire disk
# for caching, this can be the mount-point directory.
# The directory must exist and be writable by the Squid
# process. Squid will NOT create this directory for you.
# Only using COSS, a raw disk device or a stripe file can
# be specified, but the configuration of the "cache_swap_log"
# tag is mandatory.
#
# The ufs store type:
#
# "ufs" is the old well-known Squid storage format that has always
# been there.
#
# cache_dir ufs Directory-Name Mbytes L1 L2 [options]
#
# 'Mbytes' is the amount of disk space (MB) to use under this
# directory. The default is 100 MB. Change this to suit your
# configuration. Do NOT put the size of your disk drive here.
# Instead, if you want Squid to use the entire disk drive,
# subtract 20% and use that value.
#
# 'Level-1' is the number of first-level subdirectories which
# will be created under the 'Directory'. The default is 16.
#
# 'Level-2' is the number of second-level subdirectories which
# will be created under each first-level directory. The default
# is 256.
#
# The aufs store type:
#
# "aufs" uses the same storage format as "ufs", utilizing
# POSIX-threads to avoid blocking the main Squid process on
# disk-I/O. This was formerly known in Squid as async-io.
#
# cache_dir aufs Directory-Name Mbytes L1 L2 [options]
#
# see argument descriptions under ufs above
#
# The diskd store type:
#
# "diskd" uses the same storage format as "ufs", utilizing a
# separate process to avoid blocking the main Squid process on
# disk-I/O.
#
# cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n]
#
# see argument descriptions under ufs above
#
# Q1 specifies the number of unacknowledged I/O requests when Squid
# stops opening new files. If this many messages are in the queues,
# Squid won't open new files. Default is 64
#
# Q2 specifies the number of unacknowledged messages when Squid
# starts blocking. If this many messages are in the queues,
# Squid blocks until it receives some replies. Default is 72
#
# When Q1 < Q2 (the default), the cache directory is optimized
# for lower response time at the expense of a decrease in hit
# ratio. If Q1 > Q2, the cache directory is optimized for
# higher hit ratio at the expense of an increase in response
# time.
#
# The coss store type:
#
# block-size=n defines the "block size" for COSS cache_dir's.
# Squid uses file numbers as block numbers. Since file numbers
# are limited to 24 bits, the block size determines the maximum
# size of the COSS partition. The default is 512 bytes, which
# leads to a maximum cache_dir size of 512<<24, or 8 GB. Note
# you should not change the COSS block size after Squid
# has written some objects to the cache_dir.
#
# overwrite-percent=n defines the percentage of disk that COSS
# must write to before a given object will be moved to the
# current stripe. A value of "n" closer to 100 will cause COSS
# to waste less disk space by having multiple copies of an object
# on disk, but will increase the chances of overwriting a popular
# object as COSS overwrites stripes. A value of "n" close to 0
# will cause COSS to keep all current objects in the current COSS
# stripe at the expense of the hit rate. The default value of 50
# will allow any given object to be stored on disk a maximum of
# 2 times.
#
# max-stripe-waste=n defines the maximum amount of space that COSS
# will waste in a given stripe (in bytes). When COSS writes data
# to disk, it will potentially waste up to "max-size" worth of disk
# space for each 1MB of data written. If "max-size" is set to a
# large value (ie >256k), this could potentially result in large
# amounts of wasted disk space. Setting this value to a lower value
# (ie 64k or 32k) will result in a COSS disk refusing to cache
# larger objects until the COSS stripe has been filled to within
# "max-stripe-waste" of the maximum size (1MB).
#
# membufs=n defines the number of "memory-only" stripes that COSS
# will use. When an cache hit is performed on a COSS stripe before
# COSS has reached the overwrite-percent value for that object,
# COSS will use a series of memory buffers to hold the object in
# while the data is sent to the client. This will define the maximum
# number of memory-only buffers that COSS will use. The default value
# is 10, which will use a maximum of 10MB of memory for buffers.
#
# maxfullbufs=n defines the maximum number of stripes a COSS partition
# will have in memory waiting to be freed (either because the disk is
# under load and the stripe is unwritten, or because clients are still
# transferring data from objects using the memory). In order to try
# and maintain a good hit rate under load, COSS will reserve the last
# 2 full stripes for object hits. (ie a COSS cache_dir will reject
# new objects when the number of full stripes is 2 less than maxfullbufs)
#
# The null store type:
#
# no options are allowed or required
#
# Common options:
#
# read-only, no new objects should be stored to this cache_dir
#
# min-size=n, refers to the min object size this storedir will accept.
# It's used to restrict a storedir to only store large objects
# (e.g. aufs) while other storedirs are optimized for smaller objects
# (e.g. COSS). Defaults to 0.
#
# max-size=n, refers to the max object size this storedir supports.
# It is used to initially choose the storedir to dump the object.
# Note: To make optimal use of the max-size limits you should order
# the cache_dir lines with the smallest max-size value first and the
# ones with no max-size specification last.
#
# Note that for coss, max-size must be less than COSS_MEMBUF_SZ
# (hard coded at 1 MB).
#
#Default:
#cache_dir ufs /var/spool/squid 200 16 256 ←先頭に#を追記してコメント化する
cache_dir COSS /var/spool/squid/coss 100 max-size=1048576 ←追記する
# TAG: cache_swap_state
# Location for the cache "swap.state" file. This index file holds
# the metadata of objects saved on disk. It is used to rebuild
# the cache during startup. Normally this file resides in each
# 'cache_dir' directory, but you may specify an alternate
# pathname here. Note you must give a full filename, not just
# a directory. Since this is the index for the whole object
# list you CANNOT periodically rotate it!
#
# If %s can be used in the file name it will be replaced with a
# a representation of the cache_dir name where each / is replaced
# with '.'. This is needed to allow adding/removing cache_dir
# lines when cache_swap_log is being used.
#
# If have more than one 'cache_dir', and %s is not used in the name
# these swap logs will have names such as:
#
# cache_swap_log.00
# cache_swap_log.01
# cache_swap_log.02
#
# The numbered extension (which is added automatically)
# corresponds to the order of the 'cache_dir' lines in this
# configuration file. If you change the order of the 'cache_dir'
# lines in this file, these index files will NOT correspond to
# the correct 'cache_dir' entry (unless you manually rename
# them). We recommend you do NOT use this option. It is
# better to keep these index files in each 'cache_dir' directory.
#
#Default:
# none
cache_swap_log /var/spool/squid/cache_swap_log ←追記する
ファイルを保存しviエディタを終了します
COSSキャッシュストレージの作成
COSSキャッシュストレージを作成します。
[root@centos ~]# /etc/rc.d/init.d/squid stop
squid を停止中: ................ [ OK ]
#COSSキャッシュストレージを作成します
[root@centos ~]# squid -z
2010/10/04 16:05:54| Creating Swap Directories
#サービスを起動します
[root@centos ~]# /etc/rc.d/init.d/squid start
init_cache_dir /var/spool/squid/coss... squid を起動中: . [ OK ]
これで設定完了です。
