Date: Fri, 1 Dec 2017 12:30:34 +0100 From: Marek Salwerowicz <marek.salwerowicz@misal.pl> To: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Reducing the ZVOL refreservation size? Message-ID: <811b1fb1-58ba-a8f6-238f-e52b0d392c0e@misal.pl>
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Hi list, My box is running FreeBSD 10.3-RELEASE-p11: FreeBSD storage2 10.3-RELEASE-p11 FreeBSD 10.3-RELEASE-p11 #0: Mon Oct 24 18:49:24 UTC 2016 root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64 More than 3 years ago I created a 20 TB ZVOL, to be used as an iSCSI drive for Win2k8 Server. Currently the Server uses around 7 TB of the storage space. However, the total space consumed by the ZVOL is around 27TB (instead of desired 20TB). What I have noticed is that the 'refreservation' size value does not decrease while the 'referenced' size value increases. As I can predict, after filling the ZVOL with data, it will consume around 40 TB in total. Is it safe to reduce the 'refreservation' from 20 TB to eg. 15 TB? So that there will be around 5TB of storage space freed? Please find below all details for the ZVOL: #zfs get all tank1/PROD/WIN-Drive NAME PROPERTY VALUE SOURCE tank1/PROD/WIN-Drive type volume - tank1/PROD/WIN-Drive creation Wed May 21 10:53 2014 - tank1/PROD/WIN-Drive used 27.6T - tank1/PROD/WIN-Drive available 26.9T - tank1/PROD/WIN-Drive referenced 6.96T - tank1/PROD/WIN-Drive compressratio 1.00x - tank1/PROD/WIN-Drive reservation none default tank1/PROD/WIN-Drive volsize 20T local tank1/PROD/WIN-Drive volblocksize 8K - tank1/PROD/WIN-Drive checksum on default tank1/PROD/WIN-Drive compression off default tank1/PROD/WIN-Drive readonly off default tank1/PROD/WIN-Drive copies 1 default tank1/PROD/WIN-Drive refreservation 20.6T local tank1/PROD/WIN-Drive primarycache all default tank1/PROD/WIN-Drive secondarycache all default tank1/PROD/WIN-Drive usedbysnapshots 48.8G - tank1/PROD/WIN-Drive usedbydataset 6.96T - tank1/PROD/WIN-Drive usedbychildren 0 - tank1/PROD/WIN-Drive usedbyrefreservation 20.6T - tank1/PROD/WIN-Drive logbias latency default tank1/PROD/WIN-Drive dedup off default tank1/PROD/WIN-Drive mlslabel - tank1/PROD/WIN-Drive sync standard default tank1/PROD/WIN-Drive refcompressratio 1.00x - tank1/PROD/WIN-Drive written 18.0G - tank1/PROD/WIN-Drive logicalused 6.96T - tank1/PROD/WIN-Drive logicalreferenced 6.91T - tank1/PROD/WIN-Drive volmode default default tank1/PROD/WIN-Drive snapshot_limit none default tank1/PROD/WIN-Drive snapshot_count none default tank1/PROD/WIN-Drive redundant_metadata all default Thanks in advance for your help Cheers Marek -- Marek Salwerowicz
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