Re: [squid-users] How does squid choose which cache_dir to use?

From: Nicole <nmh@dont-contact.us>
Date: Wed, 22 Aug 2007 19:46:23 -0700 (PDT)

On 21-Aug-07 My Secret NSA Wiretap Overheard Henrik Nordstrom Saying :
> On tis, 2007-08-21 at 14:55 +0800, Adrian Chadd wrote:
>> It'll choose the cache dir with the least pending disk ops, if you haven't
>> configured any other restriction (min/max object size.)
>
> No, not with aufs. They internally all share the same queue.
>
> With aufs it currently basically selects the cache_dir based on amount
> of free space, or at least that's the idea..
>
>> > Normally, (when all using ufs/ffs) all the squidcache1/2/3 dirs start
>> > filling
>> > first and the cache0 dir fills slowest. However, with the 3 using zfs,
>> > cache0
>> > is filling much faster. Is this indicitive of the 3 cache_dirs using zfs
>> > are somehow slower, so its using cache0 more?
>
> Odd.. the underlying filesystem should have little or no impact on how
> Squid selects cache diretory.
>
> Regards
> Henrik

 Waah. As time goes on, it's getting even stranger. Anything I can test for or
look for?

/dev/da0s1h 39G 4.0G 31G 11% /cache0
squidcache1 134G 3.5G 130G 3% /squidcache1
squidcache2 134G 28G 106G 21% /squidcache2
squidcache3 134G 14G 120G 11% /squidcache3

-----

Server: squid/2.6.STABLE14
Date: Thu, 23 Aug 2007 02:43:15 GMT
Content-Type: text/plain
Expires: Thu, 23 Aug 2007 02:43:15 GMT
Last-Modified: Thu, 23 Aug 2007 02:43:15 GMT
X-Cache: MISS from
Via: 1.0 server:80 (squid/2.6.STABLE14)
Connection: close

Squid Object Cache: Version 2.6.STABLE14
Start Time: Wed, 22 Aug 2007 08:38:14 GMT
Current Time: Thu, 23 Aug 2007 02:43:15 GMT
Connection information for squid:
        Number of clients accessing cache: 2
        Number of HTTP requests received: 3145661
        Number of ICP messages received: 1082778
        Number of ICP messages sent: 1089324
        Number of queued ICP replies: 0
        Request failure ratio: 0.00
        Average HTTP requests per minute since start: 2899.2
        Average ICP messages per minute since start: 2001.9
        Select loop called: 56871913 times, 1.145 ms avg
Cache information for squid:
        Request Hit Ratios: 5min: 80.0%, 60min: 78.0%
        Byte Hit Ratios: 5min: 85.6%, 60min: 84.4%
        Request Memory Hit Ratios: 5min: 18.4%, 60min: 18.7%
        Request Disk Hit Ratios: 5min: 67.0%, 60min: 67.6%
        Storage Swap size: -824803418 KB
        Storage Mem size: 1024024 KB
        Mean Object Size: -508.60 KB
        Requests given to unlinkd: 0
Median Service Times (seconds) 5 min 60 min:
        HTTP Requests (All): 0.02317 0.02317
        Cache Misses: 0.03622 0.03829
        Cache Hits: 0.01955 0.01955
        Near Hits: 0.05046 0.05046
        Not-Modified Replies: 0.02069 0.02190
        DNS Lookups: 0.00000 0.00000
        ICP Queries: 0.00085 0.00080
Resource usage for squid:
        UP Time: 65100.397 seconds
        CPU Time: 3659.457 seconds
        CPU Usage: 5.62%
        CPU Usage, 5 minute avg: 6.65%
        CPU Usage, 60 minute avg: 6.54%
        Process Data Segment Size via sbrk(): 0 KB
        Maximum Resident Size: 2426132 KB
        Page faults with physical i/o: 0
Memory accounted for:
        Total accounted: 1286613 KB
        memPoolAlloc calls: 471286106
        memPoolFree calls: 465111419
File descriptor usage for squid:
        Maximum number of file descriptors: 8192
        Largest file desc currently in use: 44
        Number of file desc currently in use: 33
        Files queued for open: 0
        Available number of file descriptors: 8159
        Reserved number of file descriptors: 100
        Store Disk files open: 2
        IO loop method: kqueue
Internal Data Structures:
        1627350 StoreEntries
         41335 StoreEntries with MemObjects
         41332 Hot Object Cache Items
        1621724 on-disk objects
HTTP/1.0 200 OK

Server: squid/2.6.STABLE14
Date: Thu, 23 Aug 2007 02:43:15 GMT
Content-Type: text/plain
Expires: Thu, 23 Aug 2007 02:43:15 GMT
Last-Modified: Thu, 23 Aug 2007 02:43:15 GMT
X-Cache: MISS from
Via: 1.0 server:80 (squid/2.6.STABLE14)
Connection: close

Store Directory Statistics:
Store Entries : 1627350
Maximum Swap Size : 301056000 KB
Current Store Swap Size: -824803418 KB
Current Capacity : -273% used, 374% free

Store Directory #0 (aufs): /cache0
FS Block Size 2048 Bytes
First level subdirectories: 32
Second level subdirectories: 128
Maximum Size: 24576000 KB
Current Size: 4084006 KB
Percent Used: 16.62%
Current load metric: 100 / 1000
Filemap bits in use: 240838 of 1048576 (23%)
Filesystem Space in use: 4201740/40393146 KB (10%)
Filesystem Inodes in use: 244969/5228542 (5%)
Flags:
Accepted object sizes: 0 - (unlimited) bytes
Removal policy: lru
LRU reference age: 1.46 days

Store Directory #1 (aufs): /squidcache1
FS Block Size 131072 Bytes
First level subdirectories: 64
Second level subdirectories: 256
Maximum Size: 92160000 KB
Current Size: 21105536 KB
Percent Used: 22.90%
Current load metric: 100 / 1000
Filemap bits in use: 164019 of 1048576 (16%)
Filesystem Space in use: 3715200/140357504 KB (3%)
Filesystem Inodes in use: 180473/1247991 (14%)
Flags:
Accepted object sizes: 0 - (unlimited) bytes
Removal policy: lru
LRU reference age: 3.10 days

Store Directory #2 (aufs): /squidcache2
FS Block Size 131072 Bytes
First level subdirectories: 64
Second level subdirectories: 256
Maximum Size: 92160000 KB
Current Size: -850102016 KB
Percent Used: -922.42%
Current load metric: 100 / 1000
Filemap bits in use: 1216017 of 2097152 (58%)
Filesystem Space in use: 28991616/140344064 KB (21%)
Filesystem Inodes in use: 1232429/2102370 (59%)
Flags: SELECTED
Accepted object sizes: 0 - (unlimited) bytes
Removal policy: lru
LRU reference age: 5.08 days

Store Directory #3 (aufs): /squidcache3
FS Block Size 131072 Bytes
First level subdirectories: 64
Second level subdirectories: 256
Maximum Size: 92160000 KB
Current Size: 109056 KB
Percent Used: 0.12%
Current load metric: 100 / 1000
Filemap bits in use: 851 of 16384 (5%)
Filesystem Space in use: 14886912/140362240 KB (11%)
Filesystem Inodes in use: 647732/1628008 (40%)
Flags:
Accepted object sizes: 0 - (unlimited) bytes
Removal policy: lru
LRU reference age: 5.08 days

 Thanks!

 Nicole
Received on Wed Aug 22 2007 - 20:46:38 MDT

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