{"id":4997,"date":"2021-02-25T23:53:58","date_gmt":"2021-02-25T23:53:58","guid":{"rendered":"https:\/\/pariswells.com\/blog\/?p=4997"},"modified":"2021-02-25T23:53:58","modified_gmt":"2021-02-25T23:53:58","slug":"qnap-ghost-snapshot-thin-pool-repairing","status":"publish","type":"post","link":"https:\/\/pariswells.com\/blog\/research\/qnap-ghost-snapshot-thin-pool-repairing","title":{"rendered":"QNAP Ghost snapshot thin pool repairing"},"content":{"rendered":"

Check metadata:<\/strong><\/p>

Please use thin_check to check the metadata of the pool to confirm what wrongs in the metadata.<\/strong><\/p>

pdata_tools_8192( or 4096) thin_check \/dev\/mapper\/vg1-tp1_tmeta –non<\/p>

# Assume the ghost snapshot happen in vg1\/tp1. Please according to happened ghost snapshot pool to adjust vg${#}<\/p>

-tp${#}_tmetadata<\/p>

# if the firmware version of QTS is less than 4.3.5, please remove “–non” option<\/p>

Generally, the metadata has the below wrong:<\/strong><\/p>

<\/p>

If the metadata has no such as above wrong, please contact sustain team to analyze.<\/strong><\/p>

Backup metadata before repairing the metadata:<\/strong><\/p>

Caution!!! This is very important task!!!<\/strong><\/p>

Please must make a backup of the metadata to avoid the repairing task fail.<\/strong><\/p>

If the repairing task fail, the storage may crash. We can use the backup metadata to restore the storage.<\/strong><\/p>

Please use the below guide to make the backup of metadata:<\/strong><\/p>

https:\/\/drive.google.com\/file\/d\/14HSVV6DWSnqc7FXTSUukzJWB812Q8Tkv\/view?usp=sharing<\/strong><\/a><\/p>

Repairing flow and limitations:<\/strong><\/p>

Limitations:<\/strong><\/p>

If the storage configuration and QTS firmware versions can not meet the following condition, please contact sustain team to do repairing task.<\/strong><\/p>

1. The QTS firmware version is great or equal than 4.3.5.<\/p>

2. The chunk size of the metadata need to be 8192. Please use the below command to confirm.<\/p>

echo $((16#`hexdump -s 340 -n 2 \/dev\/mapper\/vg1-tp1_tmeta | awk ‘NR==1{print $2}’`*512))<\/p>

Repairing steps:<\/strong><\/p>

Step 1: Download “pdata_tools” which support thin_rebuild option from the below link and transfer new “pdata_tools” to the NAS.<\/strong><\/p>

# Download<\/p>

wget http:\/\/download.qnap.com\/Storage\/tsd\/utility\/pdata_tools_X86_64.zip # X86_64 version<\/a> wget http:\/\/download.qnap.com\/Storage\/tsd\/utility\/pdata_tools_ARM_64.zip # ARM_64 version<\/a><\/p>

# Unzip<\/p>

unzip pdata_tools_X86_64.zip unzip pdata_tools_ARM_64.zip<\/p>

# Please rename to pdata_tools<\/p>

mv pdata_tools_X86_64 pdata_tools mv pdata_tools_ARM_64 pdata_tools<\/p>

Step 2: Change “pdata_tools” to executable file.<\/strong><\/p>

chmod +x pdata_tools<\/p>

Step 3: Run pdata_tools with thin_rebuild option.<\/strong><\/p>

.\/pdata_tools thin_rebuild \/dev\/mapper\/vg1-tp1_tmeta # This process will execute about couple minutes or hours. Please wait for the process done patiently.<\/p>

Step 4: Use thin_check to check metadata again to confirm the “reference counts” wrongs are all fixed. If the result of thin_check still has wrongs, please contact sustain team to do the repairing task.<\/strong><\/p>

.\/pdata_tools thin_check –clear-needs-check-flag \/dev\/mapper\/vg1-tp1_tmeta<\/p>

Step 5: Restore the storage:<\/strong><\/p>

lvchange -ay vg1 # bring up the volume group storage_util –sys_startup_p2 # mount all of volumes<\/p>

\/sbin\/daemon_mgr lvmetad start “\/sbin\/lvmetad” # enable lvm cache<\/p>

\/etc\/init.d\/services.sh start # start up all of services<\/p>

 <\/p>","protected":false},"excerpt":{"rendered":"

Check metadata:Please use thin_check to check the metadata of the pool to confirm what wrongs in the metadata.pdata_tools_8192( or 4096) thin_check \/dev\/mapper\/vg1-tp1_tmeta –non# Assume the ghost snapshot […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3450,3449],"class_list":["post-4997","post","type-post","status-publish","format-standard","hentry","category-research","tag-ghost-snapshot-thin-pool-repairing","tag-qnap"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t