xfs
[Top] [All Lists]

XFS write cache flush policy

To: xfs@xxxxxxxxxxx
Subject: XFS write cache flush policy
From: Lin Li <sdeber@xxxxxxxxx>
Date: Thu, 6 Dec 2012 09:51:15 +0100
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:date:message-id:subject:from:to:content-type; bh=rIVnsDgX6kJYmSatDheyAAf/uvYdCg5YLaSM7K0Yjic=; b=U1Ztm9P9bp4WNVnPMBlD8IdzxY5nNteW71JEwtZL+k+TiEOYuYe5iiMO+avYbWmX9l RbNvRzbwBXxTrK7OgnnzNpiF2VUGq0x85H48vic7qQJoOKpia8NZzowGPRXDpm3act9q KYkaKkr8q3yzDaau3nATO88PqCL6iKdEYuukla6lTB6JvbEhm0HvD0ALgEI8SN1OI/6B hdLn4hbVCrN3TTlCCeoJjWgXz9fsgI2Gb/nBS/6SJ8h5iq14C3PmHOJH+sLsmHBe6Qrf ZZILPLRtrVKJDnpPvluWMWvH71Rdlq3Hd0+0dUDAI6tuRiyWL27QQj8qXOmbPepDL0Ax o53Q==
Hi, Guys. I recently suffered a huge data loss on power cut on an XFS partition. The problem was that I copied a lot of files (roughly 20Gb) to an XFS partition, then 10 hours later, I got an unexpected power cut. As a result, all these newly copied files disappeared as if they had never been copied. I tried to check and repair the partition, but xfs_check reports no error at all. So I guess the problem is that the meta data for these files were all kept in the cache (64Mb) and were never committed to the hard disk.

What is the cache flush policy for XFS? Does it always reserve some fixed space in cache for metadata? I asked because I thought since I copied such a huge amount of data, at least some of these files must be fully committed to the hard disk, then cache is only 64Mb anyway. But the reality is all of them were lost. the only possibility I can think is some part of the cache was reserved for meta data, so even the cache is fully filled, this part will not be written to the disk. Am I right?
<Prev in Thread] Current Thread [Next in Thread>