gistfile1.txt

```
sqlite> select * from BinaryCaches;
id          url                         timestamp   storeDir    wantMassQuery  priority
----------  --------------------------  ----------  ----------  -------------  ----------
1           http://cache.earthtools.ca  1526684947  /nix/store  1              30
2           http://nixcache.localnet    1526684947  /nix/store  1              50
3           https://cache.nixos.org     1526684948  /nix/store  1              40
4           https://hydra.iohk.io       1526684948  /nix/store  0              100
sqlite> .mode line
sqlite> select * from NARs where hashPart = "p9jg81r5cs76xkli20ylyldsx4iyqq7a" and cache = 4;
      cache = 4
   hashPart = p9jg81r5cs76xkli20ylyldsx4iyqq7a
   namePart = cardano-sl-update-1.1.1
        url = nar/p9jg81r5cs76xkli20ylyldsx4iyqq7a-cardano-sl-update-1.1.1
compression = xz
   fileHash =
   fileSize =
    narHash = sha256:0n7347rvaxwcxp69v96rnkh0mpk41gkxgjq7y1f6xgyracgyp4zr
    narSize = 13389296
...
    deriver = dxj3pi5h4wng3n2dly2p8kp848c4lps2-cardano-sl-update-1.1.1.drv
       sigs = hydra.iohk.io:vVXqSs/9IWEttavTCtt00k8LJBaWuDvGOlGPtKIVueQj8aXlE/u6gnjaUdMTuyNSnLNhY3BGAn3FbpyPjD1YCQ==
  timestamp = 1526723639
    present = 1
sqlite> select * from LastPurge;
dummy = 
value = 1527385858

[clever@amd-nixos:~/iohk/cardano-develop]$ nix-shell default.nix -A cardano-sl-wallet.env
these derivations will be built:
  /nix/store/xjzy9c6bjvzm8kmxxzszlxcmvjsw6p68-cardano-sl-1.1.1.drv
  /nix/store/c449gn2qwrr8kf0hn3f0jpy3hphfyz08-cardano-sl-client-1.1.1.drv
  /nix/store/c6714af38i5jdhz4hil6cd5cizfd1vkm-cardano-sl-generator-1.1.1.drv
  /nix/store/zwsg4lz0h0lhd2h0m5zp8mk86a4cs86c-node-ipc-0.1.0.0.drv
  /nix/store/xsrg6p3vpnmk28lvwcgfdjc1rxdlj25j-ghc-8.0.2-with-packages.drv
these paths will be fetched (0.00 MiB download, 28.93 MiB unpacked):
  /nix/store/hc1ln7j4j3hmch74bzasfcw7ijsz7sv4-cardano-sl-delegation-1.1.1
  /nix/store/hwfdckc001598zq4sfanws11p9klh5fl-cardano-sl-block-1.1.1
  /nix/store/p9jg81r5cs76xkli20ylyldsx4iyqq7a-cardano-sl-update-1.1.1
copying path '/nix/store/hc1ln7j4j3hmch74bzasfcw7ijsz7sv4-cardano-sl-delegation-1.1.1' from 'https://hydra.iohk.io'...
copying path '/nix/store/p9jg81r5cs76xkli20ylyldsx4iyqq7a-cardano-sl-update-1.1.1' from 'https://hydra.iohk.io'...
building '/nix/store/zwsg4lz0h0lhd2h0m5zp8mk86a4cs86c-node-ipc-0.1.0.0.drv'...
unable to download 'https://hydra.iohk.io/nar/p9jg81r5cs76xkli20ylyldsx4iyqq7a-cardano-sl-update-1.1.1': HTTP error 410 (curl error: No error)
cannot build derivation '/nix/store/xsrg6p3vpnmk28lvwcgfdjc1rxdlj25j-ghc-8.0.2-with-packages.drv': 1 dependencies couldn't be built
error: build of '/nix/store/xsrg6p3vpnmk28lvwcgfdjc1rxdlj25j-ghc-8.0.2-with-packages.drv' failed

[clever@amd-nixos:~/iohk/cardano-develop]$ 
[root@iohk-infra:~]# journalctl -u nix-gc | grep p9jg81r5cs76xkli20ylyldsx4iyqq7a
May 25 20:15:17 iohk-infra.ec2.hydra nix-gc-start[17839]: deleting '/nix/store/p9jg81r5cs76xkli20ylyldsx4iyqq7a-cardano-sl-update-1.1.1'
```

lines 2-8, there are 4 binary caches configured on my machine, that are being tracked in /root/.cache/nix/binary-cache-v5.sqlite
line 23, it looks like i last got a hit on this on may 19th?
line 27, nix last did a purge? on may 26th
line 43, on may 27th, at 6pm i got a 410 gone error
line 49, hydra deleted the path in question on may 25th