Synology has released an update to it’s DSM software. DSM 6.1.3–15152 Update 4 fixes some bugs that could cause data lose in some specific situations. If you use the new Btrfs file or have less than three hard drives installed then the data loss bug won’t affect you, although you should still apply the update as it contains other bug fixes.
If your NAS meets the following criteria then you’ll want to take additional steps after installing the update:
* The server is using RAID 5, RAID 6, RAID F1, or SHR with more than 3 disks.
* The volume is created on EXT4 file system.
* The server is running on DSM 6.0.2–8451 and above.
If your NAS meets the above criteria, or you just want to be safe, you’ll need to do RAID scrubbing after the update. RAID scrubbing may take several hours depending on the volume or disk group size. You can use the NAS normally, although performance may be impacted. Don’t turn off your NAS until scrubbing finished.
To start RAID scrubbing, open Storage Manager and select either Disk Group or Volume depending on your NAS configuration. (If you have disk groups available then do the scrubbing from there.) Then select Manage and run the Wizard for RAID scrubbing.
Synology has said that the following NAS models should upgrade as soon as possible as they are potentially affected by this bug.
17 series: RS18017xs+, RS4017xs+, RS3617xs+, RS3617xs, RS3617RPxs, DS3617xs, DS1817+, DS1817, DS1517+, DS1517
16 series: RS18016xs+, RS2416+, RS2416RP+, RS816, DS916+, DS716+II, DS716+, DS416play, DS416slim, DS416j, DS416
15 series: RS815+, RS815RP+, RS815, RC18015xs+, DS3615xs, DS2415+, DS2015xs, DS1815+, DS1515+, DS1515, DS715, DS415+, DS415play
14 series: RS3614xs+, RS3614xs, RS3614RPxs, RS2414+, RS2414RP+, RS814+, RS814RP+, RS814, RS214, DS414slim, DS414j, DS414
13 series: RS10613xs+, RS3413xs+, DS2413+, DS1813+, DS1513+, DS713+, DS413j, DS413
12 series: RS3412xs, RS3412RPxs, RS2212+, RS2212RP+, RS812+, RS812RP+, RS812, DS3612xs, DS1812+, DS1512+, DS712+, DS412+
11 series: RS3411xs, RS3411RPxs, RS2211+, RS2211RP+, RS411, DS3611xs, DS2411+, DS1511+, DS411+II, DS411+, DS411slim, DS411j, DS411
Synology described the bug in an email by writing:
The issue was brought to our attention a few weeks ago when the NAS communities discussed the potential data integrity threat that may occur after a RAID 5 repair. In-house investigation revealed the issue stems from Linux feature known as skip_copy. This open source feature contains a slight design fault that may lead to potential data corruption after a RAID array is repaired from degrade mode. Synology team moved quickly to identify and reproduce the issue, which is resolved in the latest DSM 6.1.3 update.
The update fixes additional issues so it is appropriate for many models not affected with the data integrity bug. The complete list of fixes is:
- Fixed HDD hibernation issues to enhance HDD compatibility.
- Enhanced overall stability of iSCSI services.
- Fixed compatibility issues with VMware environments.
- Fixed multiple security vulnerabilities regarding Linux Kernel (CVE–2017–7533, CVE–2017–10661, CVE–2017–10662, CVE–2017–10663).
- Enhanced the stability of RAID 5, RAID 6, RAID F1, & SHR.