Hello, I was wondering if someone could point me to any information describing how the l2arc works? I attached an SSD as a cache device to the root pool of a 2009.11 system. Although the cache has started filling up (zpool iostat -v) it just seems that when I do a reboot, I hear quite a bit of disk activity. I was hoping, in the best case, that most of the disk access that was needed to boot would have been served though the SSD. Does the cache fill only on writes? And what is the cache replacement policy if/when the cache becomes full? I did notice some information regarding how limiting the speed at which the l2arc populates, and I think bug 6748030 discusses a "turbo warmup". Thanks for any information. --joe -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20090702/520b5b41/attachment.html>
For now L2ARC will have to be warmed up every time a reboot happens. See 6662467. ________________________________ From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss-bounces at opensolaris.org] On Behalf Of Joseph Mocker Sent: 2009?7?3? 7:51 To: zfs-discuss at opensolaris.org Subject: [zfs-discuss] how l2arc works? Hello, I was wondering if someone could point me to any information describing how the l2arc works? I attached an SSD as a cache device to the root pool of a 2009.11 system. Although the cache has started filling up (zpool iostat -v) it just seems that when I do a reboot, I hear quite a bit of disk activity. I was hoping, in the best case, that most of the disk access that was needed to boot would have been served though the SSD. Does the cache fill only on writes? And what is the cache replacement policy if/when the cache becomes full? I did notice some information regarding how limiting the speed at which the l2arc populates, and I think bug 6748030 discusses a "turbo warmup". Thanks for any information. --joe -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20090703/f99b0403/attachment.html>
Joe, On Thu, Jul 02, 2009 at 04:50:34PM -0700, Joseph Mocker wrote:> Hello, > > I was wondering if someone could point me to any information describing > how the l2arc works? > > I attached an SSD as a cache device to the root pool of a 2009.11 > system. Although the cache has started filling up (zpool iostat -v) it > just seems that when I do a reboot, I hear quite a bit of disk activity. > I was hoping, in the best case, that most of the disk access that was > needed to boot would have been served though the SSD. > > Does the cache fill only on writes? And what is the cache replacement > policy if/when the cache becomes full?That I think is a know issue and is being worked on (bug# 6662467). For a general description about how L2ARC works refer to Brendan''s blogs at : - http://blogs.sun.com/brendan/entry/test - http://blogs.sun.com/brendan/entry/l2arc_screenshots Thanks and regards, Sanjeev> > I did notice some information regarding how limiting the speed at which > the l2arc populates, and I think bug 6748030 discusses a "turbo warmup". > > Thanks for any information. > > --joe-- ---------------- Sanjeev Bagewadi Solaris RPE Bangalore, India