# Proxy\_cache calculating size error under SSD drive but not SATA drive **URL:** \ **Category:** NGINX\ **Created:** [July 18, 2013, 1:46pm UTC](https://www.ruby-forum.com/t/proxy-cache-calculating-size-error-under-ssd-drive-but-not-sata-drive/245841 "2013-07-18T13:46:49Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\ **Post date:** [July 18, 2013, 1:46pm UTC](https://www.ruby-forum.com/t/proxy-cache-calculating-size-error-under-ssd-drive-but-not-sata-drive/245841/1 "2013-07-18T13:46:49Z")
Hello: I think I am on the right way, but not sure… The scenario: - Have 2 drives: → SSD drive - XFS - default options (with noatime, discard) - almost empty → SATA drive - XFS - default options - almost empty - Kernel variables, shared memory, ulimits, max-file, etc… all correctly configured - Nginx and virtualhost correctly configured. - proxy\_cache\_path levels=1:2 keys\_zone=catalogo\_fotos:2500m max\_size=2500m inactive=120d; Ok… here I am… it depends of the path… the problem is: - If the path is at SATA drive → cache is growing until maximum 2500m are reached… no problem here. Normal… - If the path is at SSD drive → cache is not growing until limit… it stale… problem… why? If debug see: 2013/07/18 13:15:52 [debug] 17641#0: http file cache size: 640039 2013/07/18 13:15:52 [debug] 17641#0: http file cache forced expire 2013/07/18 13:15:52 [debug] 17641#0: http file cache forced expire: #0 1 933590ab 2013/07/18 13:15:52 [debug] 17641#0: http file cache expire: “/DATA/cache/catalogo\_fotos/7/3a/c1de7a39f5393c24933590ab20ba43a7” while: root@megaserver1 /DATA/cache # du -hs catalogomodacom\_fotos/ 1.8G catalogo\_fotos/ root@megaserver1 /DATA/cache # find ./catalogo\_fotos/ -type f | wc -l 17134 What happens? Every 10 seconds, http file cache size detects max size and starts to force expire and delete cached files… What is that “http file cache size: 640039” ??? That number, which way is calculated??? What it is? I have enough shared memory, already properly configured (1Gb for each app and 14Gb total)… and the question is if I change path and set it under SATA drive there is no problem. I am thinking at all at this “http file cache size: 640039”… I think it is the key about what is happening… that number is not near the max size of 2500m defined for the cache deposit, and is not near the number of files actually at cache, around 17134… Could you help me please? Thanks so much in advance. Gino. Posted at Nginx Forum: > **[proxy\_cache calculating size error under SSD drive but not SATA drive](https://forum.nginx.org/read.php?2,240993,240993#msg-240993)** > > Hello: I think I am on the right way, but not sure... The scenario: - Have 2 drives: -\> SSD drive - XFS - default options (with noatime, discard) - almost empty -\> SATA drive - XFS ---
**Author:** ![feanorknd](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/ec9cab/32.png) [@feanorknd](https://www.ruby-forum.com/u/feanorknd)\ **Post date:** [July 18, 2013, 4:44pm UTC](https://www.ruby-forum.com/t/proxy-cache-calculating-size-error-under-ssd-drive-but-not-sata-drive/245841/2 "2013-07-18T16:44:27Z")
Hello! On Thu, Jul 18, 2013 at 07:46:01AM -0400, feanorknd wrote: > empty > Ok.. here I am… it depends of the path… the problem is: > > - If the path is at SATA drive → cache is growing until maximum 2500m are > reached… no problem here. Normal.. > - If the path is at SSD drive → cache is not growing until limit… it > stale… problem… why? Try looking into this ticket: > **[\#157 (cache max\_size limit applied incorrectly with xfs) – nginx](https://trac.nginx.org/nginx/ticket/157)** With XFS, a file size reported on just created files before a file is closed is incorrect, and this might confuse nginx. […] > What is that “http file cache size: 640039” ??? That number, which way is > calculated??? What it is? This is the cache size in blocks. – Maxim D. > **[nginx: donation](http://nginx.org/en/donation.html)** ---
**Author:** ![feanorknd](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/ec9cab/32.png) [@feanorknd](https://www.ruby-forum.com/u/feanorknd)\ **Post date:** [July 19, 2013, 2:55am UTC](https://www.ruby-forum.com/t/proxy-cache-calculating-size-error-under-ssd-drive-but-not-sata-drive/245841/3 "2013-07-19T02:55:38Z")
Thanks thanks so much!!! 😃 I even saw that ticket before posting, but I figured out it was not the problem just because I do use XFS for my nginx\_caches at 4 servers without this problem, and also I did test changing the path to point to a XFS partition on SATA drive, and the problem dissapeared. If you have a look at the ticket, that user also use a SSD drive and have the alloc problem… it seems like if only at SSD drives, the size notification is incorrect because of the allocsize, but not on SATA drives, although the allocsize is default for both of them, at least in my case!!! Have a look at my first post and see at SATA drive, with XFS defaults, the cache gets fullfilled exactly and if I configure 2500Gb, the “du -hs” when core starts force expiring objects, is just that 2500Gb… the measures al exact and real. Not the same for SSD.. do you think people is something to review by developers somehow? Thanks. ## Maxim D. Wrote: > [nginx: donation](http://nginx.org/en/donation.html) > > * * * > > nginx mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [mailman.nginx.org archive](http://mailman.nginx.org/mailman/listinfo/nginx) Posted at Nginx Forum: [http://forum.nginx.org/read.php?2,240993,241022#msg-241022](http://forum.nginx.org/read.php?2,240993,241022#msg-241022) ---
**Author:** ![feanorknd](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/ec9cab/32.png) [@feanorknd](https://www.ruby-forum.com/u/feanorknd)\ **Post date:** [July 19, 2013, 12:05pm UTC](https://www.ruby-forum.com/t/proxy-cache-calculating-size-error-under-ssd-drive-but-not-sata-drive/245841/4 "2013-07-19T12:05:58Z")
Hello! On Thu, Jul 18, 2013 at 08:54:48PM -0400, feanorknd wrote: > although the allocsize is default for both of them, at least in my case!!! > > Have a look at my first post and see at SATA drive, with XFS defaults, the > cache gets fullfilled exactly and if I configure 2500Gb, the “du -hs” when > core starts force expiring objects, is just that 2500Gb… the measures al > exact and real. > > Not the same for SSD.. do you think people is something to review by > developers somehow? Depending on media used XFS might apply different defaults, and/or observed behaviour might be different due to timing reasons. Quick search suggests XFS currently uses dynamic allocsize by default, see here: > **[xfs: dynamic speculative EOF preallocation - kernel/git/torvalds/linux.git -...](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=055388a3188f56676c21e92962fc366ac8b5cb72)** Try forcing allocsize to something like 4k to see if it helps. – Maxim D. > **[nginx: donation](http://nginx.org/en/donation.html)** ---
**Author:** ![feanorknd](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/ec9cab/32.png) [@feanorknd](https://www.ruby-forum.com/u/feanorknd)\ **Post date:** [July 18, 2013, 2:32pm UTC](https://www.ruby-forum.com/t/proxy-cache-calculating-size-error-under-ssd-drive-but-not-sata-drive/245841/5 "2013-07-18T14:32:59Z")
Hello: Each 10 seconds, the core force expires files until http cache size below 640000 (limits are defined at 2500Mb at config) grep “cache size” /STORAGE/log.txt 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640339 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640317 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640297 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640262 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640248 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640236 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640226 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640217 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640207 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640197 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640167 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640157 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640141 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640124 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640115 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640057 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 640040 2013/07/18 13:15:22 [debug] 17641#0: http file cache size: 639904 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640192 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640188 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640154 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640115 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640106 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640097 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640083 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640074 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640050 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640042 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640026 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 640011 2013/07/18 13:15:32 [debug] 17641#0: http file cache size: 639997 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640397 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640380 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640368 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640343 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640330 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640306 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640158 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640149 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640139 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640130 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640119 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640110 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640101 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640092 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640072 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640062 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640049 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 640025 2013/07/18 13:15:42 [debug] 17641#0: http file cache size: 639944 Hope it helps… For the proccesor, the max http file cache size is 640000 (but only for this proxy\_cache… i have more!!!) Thanks. Posted at Nginx Forum: > **[Re: proxy\_cache calculating size error under SSD drive but not SATA drive](https://forum.nginx.org/read.php?2,240993,240995#msg-240995)** > > Hello: I think I am on the right way, but not sure... The scenario: - Have 2 drives: -\> SSD drive - XFS - default options (with noatime, discard) - almost empty -\> SATA drive - XFS